How One Unheralded Platoon of GIs Helped End the War in Korea ........In recent years I have reviewed three different video documentaries on the Korean War totaling some 10 hours. Each was presented as the complete story of "The Forgotten War." Yet, in all of those 10 hours of coverage, no more than 10 minutes total was devoted to events that took place during the last half of the war. Many written histories provide a similarly unbalanced perspective on the conflict.........The Korean War went on for 37 months—from June 25, 1950, to July 27, 1953. In actual fact, it was not a single war, but two very different wars…and that appears to be the problem with historical accounts of the conflict. For the first 17 months of the war, the two sides fought over control of the Korean countryside, with battle lines—at different times—moving virtually from one end of the country to the other. Then, in November of 1951, with the main line of resistance (MLR) straddling the 38th Parallel—where the war had begun—peace talks were initiated and the level of combat was reduced to what commanders on our side termed "active defense." It is at this point in time that most histories of the conflict terminate their coverage of the events of the war itself. ........"Stalemate" is how these histories describe the nature of the continuing conflict as the peace talks dragged on for the next 20 months. Certainly that term accurately characterizes the frustrations being experienced among peace negotiators in Panmunjom. But, among the GIs in the bunkers along the MLR, continued mortal combat stood as a vivid reminder that they were still very much at war, particularly when, after about six months of stalemate, active defense gave way to a new war—The War of the Hills. ........Passing off these last 20 months of the war as being worthy of no more than a few brief comments in recorded histories of the conflict demeans the service of those brave men who served out their tours of duty in Korea during that part of the war. U.S. Army units engaged in combat during the stalemated peace talks sustained a total of 25,524 casualties, including 4,798 killed in action, 494 missing and declared dead and 254 captured, four of whom died in captivity. Among the other U.S. services, which only recorded fatalities, the Marine Corps lost 1,932; the Air Force 456 and the Navy 193 during that period. More telling perhaps are the 40 Medals of Honor awarded during the last half of the war. ........Arguably the most unfortunate aspect of history’s neglect of the last 20 months of the Korean War is the implicit suggestion that those GIs who maintained the MLR during those final months were simply marking time until the Panmunjom negotiators came to terms for a peace agreement. The fact is, it is most unlikely that an agreement would have come nearly as early as it did had it not been for those GIs doggedly making the conflict too costly for Communist forces to continue. Here is how just one small group of those unheralded GIs helped convince the enemy to end the fighting. ........This story begins early in the morning of March 23, 1953, at the headquarters command post of the U.S. 31st Infantry Regiment (code name Bearcat). At that time, the 31st occupied front-line positions in a sector of the MLR just west of what was once the North Korean city of Chorwon. Included in that sector were two outposts that had already achieved a considerable level of notoriety—Old Baldy and Pork Chop Hill. That morning, I stood in front of the desk of the Regimental Intelligence Officer (S2) and made a plea for permission to move my men off of Old Baldy. To help you understand why I was making the request, I need to tell you a little about what those men were doing out there. 
........The table of organization of every U.S. Army infantry regiment involved in fighting the war in Korea included a small group of technical specialists known as the Counterfire Platoon. The mission of the men in this platoon was to provide information on the location of enemy weapons so that they could be neutralized by return fire. The method they employed was "sound ranging," so called because the sound of the muzzle blast of an enemy weapon was used to determine its location. Because the success of sound ranging equipment depends on the ability of the counterfire specialist to hear the muzzle blast when the weapon was fired, our observation posts (OPs) had to be located as far forward as the tactical situation would allow. And, because Old Baldy was an outpost more than a thousand yards forward of our front-line positions, it should have been an ideal location to listen for enemy weapons being fired. It should have been, but it wasn’t. A photo of Old Baldy, as it looked a couple of months later, is shown above. The elevation in the foreground was called Westview.........The main problem was background noise. When you are that far forward in a combat zone, the sounds of battle are always with you. Even though the specialist himself could often distinguish the blast of an enemy mortar or artillery piece through that noise, the equipment we used to pinpoint the sound could not. In addition, the alignment of the equipment, which was essential for accurate measurements, could be disturbed by heavy incoming fire—and incoming fire had been increasing steadily in recent days on Old Baldy. I’ll discuss more about all of that equipment later. For now it is sufficient to say that my counterfire OP out on Old Baldy was unable to do its work and I needed to move the men back to the MLR where, although farther away from the enemy gun positions, they were not so hampered by noise and incoming. That was my plea to the Regimental S2. ........Fortunately, he agreed. As it turned out, it was a lot more fortunate than I had anticipated—particularly for my men from the Old Baldy OP. By about 1600 that afternoon, I had them off of the outpost and situated in a new OP back on the MLR. By midnight that night, it was being overrun by a horde of Chinese regulars. ........At that time, Old Baldy was being occupied by the Colombian battalion that had been attached to the 31st as part of the United Nations mobilization for the war. Offering fire support for that sector of the front was the U.S. 57th Field Artillery Battalion, which had assigned as an artillery forward observer with the Colombians 2nd Lt. Albert De La Garza, Jr. from San Antonio, TX. The counterfire OP on Old Baldy had had a close relationship with Lt. De La Garza, because they were about the only Americans on the hill. So, we were all dismayed the next morning to hear that the forward observer was reported missing after the battle and was assumed to have been taken prisoner. That assumption was confirmed in the next few days, and it was also learned that he had been wounded in the assault. All of this, of course, would seem to have little bearing on the story…except for what happened a month later. ........During the week of April 20 to 26, 1953, 149 sick or wounded U.S. POWs were returned by the Chinese in a prisoner exchange called Operation Little Switch. Lt. De La Garza was included in that exchange. Before being evacuated back to the States, he was debriefed by military intelligence. In his debriefing, the lieutenant recounted persistent interrogations by his captors. One of the questions they had badgered him to answer was, "What makes your counterfire so effective?" When news of the forward observer’s Chinese interrogation trickled down to the men of Bearcat Counterfire, we were delighted to hear that we had been giving them that much trouble. And we were pretty sure we knew what made them so upset. ........It was common practice with the Chinese at that time to set up their weapons, fire off a few rounds and then quickly withdraw back into their caves. But, when a Chinese cannoneer pulled the lanyard on a weapon aimed in our direction, it was very possible that he would not live to pull it again—and his commanders would find devastation where he and their guns had once been. Three minutes. That’s how long it took—from the time a round from one of their guns impacted in our sector till we had six rounds of 105mm HE (high explosive) exploding on the weapon that fired it. What made so quick a response possible? Read on, and I’ll tell you 
........Successful sound ranging involved two key ingredients: 1) a highly skilled counterfire specialist; and 2) some very sophisticated (for that day) electronic equipment. To establish the direction to the source of a sound, you first need an array of three microphones set up in such a way that the sound wave would reach each of them at a slightly different time. These microphones were tied together so that, when one of them was fixed to the ground, the other two would stretch into an accurately-measured right isosceles triangle, such as the one in the illustration. The length along the key azimuth was about 20 feet.........Ideally that azimuth should be surveyed in, but circumstances seldom allowed that to be possible. The microphones needed to be out in the open where they had the best chance of picking up sounds from the direction of the enemy—which was usually in full view of their observers. So, to avoid allowing them to see where we were and what we were up to, we had to sacrifice survey precision in establishing the key azimuth. Most often, the direction of that arm of the array had to be determined by a sound ranging specialist on his belly in half-light using a GI compass. In fact, these expedient methods were usually very adequate, as the complaints from the Chinese testified. ........The photograph below was taken in front of the counterfire OP bunker on the MLR to which the Old Baldy OP had been moved (OP#6). In the upper left corner you will see a microphone (mike #1) from the array for that OP. The two officers in the photo are the author (on your right) and his replacement as Counterfire Officer, Lt. John Nisbet. 
........Also visible in this photo are wires running from the microphones in the array into the bunker, where they were connected to equipment that would record and analyze the sounds. That equipment consisted of a closed-loop recorder and a "black box" containing electronics that converted the sounds into patterns on an oscilloscope. The recorder rotated a steel tape, repeating the cycle several times a minute. Each microphone in the array was connected to a recording head in the machine. Before any recording session, each head was positioned at a specified base position in the loop. Erasing heads were also in the loop, one immediately before each recording head, so that sounds were repeatedly recorded and erased as the tape rotated.........The recorder could be turned on and off by means of a thumb switch on a long cord that could extend well into the trench outside the bunker. When the recorder was turned on, it ran continuously, recording and erasing whatever was being picked up by the microphones. If, while it was on, the sound ranging specialist heard a muzzle blast from an enemy weapon, he had about five seconds to press the thumb switch to turn it off. If he waited longer, the sound would be erased from the recording loop. ........Once a suspected muzzle sound was recorded on the tape, the "black box" in the bunker was put to work. In essence, here was what the process of analysis involved. Because the tape rotated at a specific speed, the location of each sound on the tape could be translated into a relative time that the sound reached each of the microphones. If you look at the layout of the array shown on the previous page, you can see that, whatever the direction from which the sound originated, the waves would hit the microphones at a predictable sequence of times. So, once the specialist had determined that sequence from the "black box," he could use a special circular slide rule to calculate the azimuth from the OP to the enemy gun that had fired the round. ........It all seems simple enough, but in fact it was anything but simple. Even though, on the MLR, we were not subject to the volume of incoming we had experienced out on Old Baldy, our microphones could be easily thrown out of alignment by a near miss from a periodic round of harassing fire. Or, more often—and considerably more frustrating—they could be uprooted by a GI taking a shortcut over one of our hills at night. And background noise remained an irritating problem. However, the biggest demand on our resources—trying to keep the OPs up and running when we needed them—was the energy demand of the equipment. ........The energy supply for our equipment came from a six-volt lead-acid storage battery—the same kind that were used at the time in our jeeps and trucks. Because the motors and vacuum-tube electronics in our system had such a high energy demand, we could not afford to waste energy waiting around with the equipment turned on hoping for the enemy to shoot something at us. Typically, the specialist had to wait till a weapon was active—usually after the first round hit the ground in our sector—to turn on the recorder and take up a listening position in the trench. Then, he had to wait till another round was fired to catch that muzzle blast on the recorder. If he caught a clear sound, he quickly set to work calculating the azimuth to the enemy gun…and then quickly turned off the equipment. ........We usually maintained one extra battery in each of our front-line OPs. But, with six OPs extending across more than five thousand yards of MLR—and the only available charger located at our headquarters some ten miles to the rear, keeping power available to our OPs was a major logistical effort. Virtually every day, someone had to make a trip to provide a fresh battery—or other needed supplies—to one or more of the OPs. And, because all of our locations were on the highest elevations we could find, it meant a steep climb carrying a heavy battery on almost every trip. Clearly, effective sound ranging depended as much on physical endurance as it did on a trained ear and facility with the "black box." ........Of course, even when the sound ranging specialist has done his job quickly and efficiently, all he has to show for it is a single azimuth—the direction from his OP to the active enemy gun. The weapon could be anywhere on that azimuth line. Obviously, additional information would be needed to find the exact location of the gun. To solve that problem, the Army field manual on sound ranging operations specified that counterfire OPs should be set up in pairs, with their electronics connected together such that the two recorders could be stopped together when a specialist in either OP heard the sound of an enemy weapon. In principle, that makes perfect sense. If two OPs, separated by 500-1000 yards, each calculated an azimuth to the same weapon after their microphones recorded the same muzzle blast, the two azimuth lines should intersect at the exact location of the weapon. Indeed, that was the way it was supposed to work…but it never did—at least for us it didn’t. ........We tried a number of times to connect adjacent OPs together the way the field manual specified, but was just too difficult to maintain the integrity of the two communication lines required to make things work; one line connecting the recorders and another for voice communication so that the specialists could coordinate their efforts. We did occasionally get intersecting azimuths from two different OPs, but that was a matter of chance rather than intent. In fact, our success didn’t typically come from intersecting azimuths. It came from the intelligent use of intelligence (more about that later)…and from the way we were organized to do our work 
........The adjoining graphic shows a topographic map of a portion of our sector, indicating the MLR and the locations of five of the six OPs. The sixth OP was featured in an earlier photo and is off this map to the northeast. The scale of the map is 1:50,000 and the distance in elevation between contour lines on this map is 20 meters (65.6 feet). Shown below is a photo of the author with the men from OP#1 outside the bunker that housed them and their equipment. The wires coming from the left in the photo lead from their microphone array on the crest of the hill above the bunker
........Because of the relatively stable tactical situation in Korea during the War of the Hills, things could be organized to take maximum advantage of those circumstances. It was of particular advantage to the field artillery, because they were able to place their guns in specified positions and never move them. They could zero in every significant location within reach of their weapons and be dead accurate on any mission by using only map coordinates. In our division (the 7th Infantry Division), each of the three integral 105mm howitzer battalions was attached for tactical purposes to one of the division’s three regiments. The 57th FA Battalion was attached to the 31st Infantry and, because the business of regimental counterfire required an intimate relationship with the people on our side who could shoot back, Bearcat Counterfire was attached to the 57th.........Our operation was headquartered at the command post of the 57th, and it was there that we carried on support operations for the men in the OPs up front. It was there that we maintained our repair shop, battery chargers and supply stores. It was there that we maintained the personal gear of the men in the OPs, and a bunk for them to bed down when they were rotated off the hill for a couple of days of rest. That rotation policy was made necessary by the fact that our unit was never relieved from front-line duty—even when our regiment went back for a rest. To my knowledge, Bearcat Counterfire occupied those same OPs from the time the division took over that sector of the MLR till the armistice was signed some seven months later. And that was one of the wisest decisions the big brass ever made. ........Being an effective sound ranging specialist was more than having a good ear and easy facility with the "black box." He had to know the terrain in front of him like the back of his hand. He had to know how different weapons sounded when they fired—and impacted—in that terrain. And he had to have a special feel for how the enemy in his sector carried on the business of making war. These abilities could only be acquired and maintained by spending extended periods of time in one place. Although, that might seem unfair, we really didn’t mind having permanent assignment to the front lines while the other GIs were getting periodic reserve time in the rear area. For us, there were sufficient benefits to our arrangement that no one ever complained. 
........For a primarily technical operation—one that thrived on a minimum of intrusion by the brass—ours was a situation made in heaven. We were an infantry outfit attached to the field artillery. We were orphans. The folks at regiment considered us to be the responsibility of the guys at the 57th, and they ignored us. The people at the 57th provided us a place for our headquarters and, otherwise, left us alone to do our work. I have always felt that this arrangement contributed significantly to our success doing that work.........The photograph on the right shows the view in front of OP#4. You can see from this photo (and from the topographic map of the region ) that we had the advantage of ideal terrain for doing our work. There were no high mountains in the area to interfere with the sounds, and our observers had almost unlimited line-of-sight in all directions. ........Operations at the 57th Field Artillery Battalion were carried on at the battalion fire direction center (FDC). Because of the stable tactical situation, fire direction operations for all three batteries in the battalion were performed there. The FDC bunker at the 57th housed the artillery fire direction specialists that calculated the parameters needed to aim their guns at targets requested by forward observers or others (like the counterfire platoon) that reported targets of opportunity. These specialists were supervised by the fire direction officer, who selected which missions to fire and then provided the initial data necessary for his crew to do their work…and a most remarkable crew they were. As I watched them over the months, I never ceased to be amazed at the speed and efficiency with which they calculated aiming solutions and communicated them to the guns. ........Next to the fire direction officer’s desk in the FDC, Bearcat Counterfire had its plotting center. It consisted of a switchboard (with lines to each of the OPs) and a large map table on which were affixed maps revealing the entire division front and all enemy terrain from which their weapons could reach our emplacements. Next to the switchboard was an erasable chart on which data from the OPs could be recorded. This chart was the first key in the business of "connecting the dots"…the intelligent use of intelligence. In that business, the prime credo was "no detail is unimportant!" An illustration of such a chart is shown below. 
........Without the regular ability to pinpoint the locations of enemy guns from intersecting sound-range azimuths, we had to use every bit of other intelligence we had available to do our job. A lot of critical intelligence appeared on the chart as the men in each OP reported what they saw and heard. It was the job of the people in the plotting center to sort through that intelligence—along with other sources of useful data—to determine whether or not we had sufficient reliable information to request a fire mission on an enemy weapon position.........The topographic map itself was our first source of useful information. Our map table was about five feet long and half that in width. The 1:25,000 scale maps on it covered everything we had to be able to locate on both sides of the MLR. On these maps, the locations of each of the OPs was indicated, so that what had been determined on the ground could be duplicated on the map. That is, if an azimuth had been calculated from an OP, the plotting center had to be able to reproduce that azimuth on the map. To make this possible, an arc was drawn on the map indicating compass directions from each of the OPs. Go to the map with that overlay, showing the compass arc from OP#4. ........To reproduce the azimuth on the map table without actually drawing on the map, we used an overlay of clear acetate with one side sufficiently rough that it would accept a pencil mark. With that overlay in place, and with a pin in the location of the OP reporting the azimuth, we drew a pencil line through the compass arc at the azimuth indicated. Somewhere on that line was the weapon we wanted to neutralize. However, unless we had an intersecting azimuth to the same weapon from another OP, we needed more information. ........One source of possibly helpful information was sent every couple of days from Division G2 (Intelligence). This was an updated list showing the coordinates of known or suspected enemy artillery and mortar emplacements. I have mentioned that the Chinese tended to move their weapons frequently, so it was imperative that we continuously update our list with the most current data indicating their possible whereabouts. The data on this list included both the location and the most likely caliber of the weapon. These data came from aerial reconnaissance and a variety of other sources—including counterfire operations like ours. Whenever we located a weapon by sound ranging that was not on the G2 list, we reported it promptly for addition to the next update. Each time we received an update, the data were quickly added to a map overlay showing all known and suspected enemy weapon locations. Go to the map including that overlay. ........When this overlay was placed over the map and its first overlay, the one indicating the azimuth line reported by the OP, you could immediately see whether or not the line passed over the location of a known or suspected enemy weapon of the reported caliber. In our experience, it often did...as with the example azimuth on the OP#4 overlay. Very often, however, the azimuth line did not indicate any specified position for that caliber weapon. So we needed to draw on additional information. The contours on the map itself were often able to provide that information. 
........When you have been routinely reading topographic maps for months, the terrain indicated by the contour lines tends to jump out at you as if you were looking at it directly. So, when we were looking on the map for the possible location of an enemy gun emplacement, the contours could tell us sometimes where the most likely possibilities would be. To assist us in this endeavor, we needed one more kind of data—the maximum effective range of each of the weapons in the enemy’s arsenal. These figures we could obtain from division intelligence. Then, each of these distances was copied as an arc on a fan-shaped overlay using the same scale as the map on our plotting board. This overlay is illustrated in the graphic shown on the right. (Note: This illustration is not intended to represent the actual relationships among the ranges of the weapons indicated, but simply to demonstrate the construct of the overlay.)........To use this overlay, a pin was placed into the map board at the coordinates of the impact. Then, when the overlay was placed over the azimuth line to the enemy weapon, with its vertex at the pin, you could determine how much terrain along the line needed to be examined to find the possible location of that kind of weapon. In the terrain we were working in at the time, this was a useful exercise and occasionally gave us a likely target for our counterfire. ........These were the collection of tools used by Bearcat Counterfire to connect the dots…to quickly locate where active enemy weapons were located and to eliminate them. In a conflict like the War of the Hills, the victor will most often be determined by which side is first to make the other pay too high a price to continue. That’s what we did in the final months of the war in Korea. * A condensed version of this report was published in Military Heritage, February 2006, pp. 20-25. Richard E. Ecker
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