Success at war is made up of three parts: brains, brawn and assets. One of the Signal Corps’ jobs is to make sure that when it comes to communications at least, we have the brains to figure out what assets are needed, the brawn to put them in place and the ability to add to the assets as required to keep the lines of communication open. In the Korean war one of the assets that needed to be taken care of and kept operating was the Mukden Cable, a communications link that stretched from Mukden (known as Shenyang in Chinese) in China, down the Korean Peninsula and then across the Korean Strait/Sea of Japan to Japan.

As most know today, the Mukden Cable provided the backbone needed to link Japan to Korea and China during that time when Japan occupied both Korea (1910 – 1945) and northeastern China (then called Manchukuo, or “Manchu country”). The Mukden Cable was designed to provide the key communication link between Japan and these fledgling members of its new empire, so that she could maintain both economic, military and political control over these newly occupied territories.

Originally built by the Japanese through slave labor from both Korea and China, on its opening on September 30, 1939, it was the longest communication cable in the world, stretching some 2,700 kilometers along its full length. Interestingly, it took the Japanese only 4 years to lay the cable, install the repeater stations, and make the whole thing operational. To honor their accomplishment the cable was put into service with a celebration hosted by Japan’s Minister of Communications, Nagai Ryutaro. Speaking from the terminus of the cable in Tokyo, he described the accomplishment as a “revolutionary invention” and went on to say:

“As the longest cable in the world, completion of the Japan–Manchukuo connection telephone cable has become the focus of all the countries. This cable is not an imitation of the West but was completed with the unique technology on the basis of the Ministry of Communications’ research and invention; it is significant as the pride of a scientific Japan. In today’s world, full of uncertainties, I believe that as the only leading country of colored people firmly established in the corner of East Asia, Japan has a cultural mission that is both real and grave. Considering the great mission of building the new East Asia that has now fallen on the shoulders of the Japanese people, we are more acutely aware of the responsibility of constructing an East Asian telecommunication network as the first step.”[1]

The reader can see that as far as Japan was concerned, the Mukden Cable was to play an important part in helping Japan create its much heralded East Asian Co-prosperity Sphere, and was destined to support Japan’s efforts to mimic British, French and German imperialism as it took control of China and Korea. As Japan so clearly said, it was time that it, as the leading nation of the “colored people… of East Asia” got on with making East Asia as powerful as the countries of the West. 

When the Korean War got underway it became equally as clear to the U.S. that this link had to be kept operational. Functionally, the link depended on repeater stations that were built and operated by the Japanese, back when they were in charge. At the time of the break out of the Korean War, the Japanese by then being long gone, the cable and the repeater stations were being maintained and operated by the Ministry of Communications of the Republic of Korea.

The cable itself was a different story. Constructed of ten quad-pairs that in turn were made up of two twisted-pairs of wire each, in most places the cable was buried little more than a meter underground. To make it easy to find, the Japanese had obligingly buried it along the length of the Pusan–Mukden highway. Thus, anyone wanting to could simply walk along the highway… which stretched from Mukden in northeastern China to Pyongyang and then on to Seoul and Pusan… walk one meter in from the edge of the highway, and start digging. By the time they got down to a depth of one meter they would have found it. Imagine that: one meter in, and one meter down for 2,700 kilometers. It appears that even back then the Japanese were ahead of the world in terms of quality control standards.

Ease of location aside, the cable depended on repeater stations at Miryang, Taegu, Kumchon, Yusong, Chonan, and Osan to keep its signal strength up. Six repeater stations in six of the toughest fighting areas of the Korean War.

To keep this marvel of engineering running MacArthur called on the boys of the 71st Signal Service Battalion. And while the 3 Officers and 19 enlisted men that would initially have the privilege of providing the brains, brawn and assets required  to keep this beast humming may not have known how important they were to the war effort, the stars did, as they aligned to alter time so that the men arrived on the 4th of July, in 1950. They also aligned to see that Capt. Wayne A. Striley,[2] a U.S. Army Signal Corps OCS graduate of Class 43-19, went along in command.

When Striley and his men arrived in Pusan they found that the cable was operating as far as the front lines. Since the rear echelon sections of the cable seemed to be in operational order, they focused on keeping the forward area working. Bedded down in Pusan, they made day trips to the front line area, following the highway and checking every step along the way on the condition of the cable, repairing any breaks they found.

Students of the Korean War know that the U.S.’ position in July of 1950 was not too good, and that MacArthur’s troops were about to be driven back. It was no wonder then that in one of his first efforts to survey the cable at the front Captain Striley was only able to get as far as Yusong before encountering the meat grinder that was the Korean War. Seeing little chance for the wire foreman and a cable splicer he had brought along to get any work done, Striley sent the men back to the rear, thinking he would simply wait until the front line moved a bit further before continuing. Instead, as July wore on, the line was driven back.

With a sense of humor, Striley reported that the fall back made things easier for him, as he now had less cable to maintain. His only concern was that if the U.S. and ROK troops kept falling back he would work himself out of a job, as there would be nothing left to keep operating.

In a more reflective mood, and believing of course that the Army would prevail in its fight with the North Koreans, he ordered that neither the cable nor its repeater stations be destroyed as troops fell back, as they would surely be needed again when the infantry boys decided to march forward instead of backwards.

The war dragged on through the summer of 1950, and it wasn’t until September that the U.S. made its push to breakout from the Naktong perimeter. During that breakout Captain Striley’s men were supplemented with men from other communication groups in the area, each taking on a separate responsibility for bringing the Mukden Cable back on line as the front line advanced.

As the war slowly began to go our way, Captain Striley’s detachment was assigned to move in lock step with the infantry—and he did that—all the way back to Yusong where he had been just a few months earlier.

As the battle progressed the cable proved easy to repair, and it only took the men a few days to get everything humming again once an area was recaptured… or at least that was the case up to Yusong. After Yusong the infantry got its breath back and really picked up the tempo. From that point forward the fighting not only became more fierce, but the Infantry more determined to push the North Koreans back, by greater amounts each day.

Day after day Captain Striley saw the front line move forward, faster than his men could keep up, even though they worked around the clock to repair the cable. And once the Infantry linked up with the U.S. forces coming down from Inchon and Seoul, the race was on and the Infantry simply disappeared into the haze of war that sat on the horizon. With no chance of keeping up with the front line as it went north, Captain Striley and his men set about doing what they did best… repairing a cable system and bringing in online as fast as they could.

With each step along the road the men of the 71st Signal Service Battalion found that the cable seemed in worse condition than the day before. Looking today at the reports they submitted back then, it’s clear that the damage they were seeing was localized to those spots where the fighting was heaviest. In those places the cuts and breaks to the cable were almost too numerous to splice. This makes perfect sense, as the average artillery shell usually dug a hole deeper than the one meter depth that the cable was buried at. Fortunately, tone locating devices allowed cable operators to pinpoint cuts to the cable pairs within two miles of the actual damage, which made it easier for Striley’s men to find the damage. All they had to do was follow the cable and look for artillery shell damage, or other destruction from tanks, mortars or aircraft bombs. When they found a place with lots of holes and trees down, they usually found the break they were looking for.

Fixing broken pairs was one thing, that was doable with ease. What was more of a challenge was figuring out where the North Koreans had tapped into the cable to pick up a pair of wires to serve their own local communication needs, and where they had broken out of it at the other end. This sort of piggybacking of North Korean communication links on top of the cable’s links caused innumerable short circuits, many of which couldn’t be fixed. The result was that cable pairs often had to be reassigned at each station and point along the entire length of the cable. The problem of short circuits also forced the men to track each cable pair and what condition it was in, so that if a cable pair was abandoned and further up the road someone was able to find the exit point of a tapped pair that caused it to be abandoned in the first place, then a cable splicer could be sent back down the road to the point where the pair was abandoned, to reset the cable pair configuration back to its ‘natural’ order. Adding to all of this was the problem of some pairs simply not being strong enough to carry a carrier wave. Since testing each cable pair after repairs were made would slow down progress and keep the men from ever catching up with the Infantry, it was decided that when the cable was found to be cut only a temporary splice would be made. Later, when the time allowed or more men were available, others would be sent back to finish the job and clean up the splice. While different than how splices were made in World War II, this approach sufficed in Korea because there was a real need to get the cable working all the way up to where the Infantry was fighting as fast as possible, and the destruction that was found along the way was so extensive that if everything was brought back to A1 condition before the Signal boys moved on, the Infantry would never be seen again.

Looking from today’s perspective, it seems evident that there weren’t enough cable splicers or line men to get the job done in the time required. But then again, that was the case with Infantrymen too. The difference with the Signal Corps was that they were able to bring civilians in from the States and pay them high wages to fill in the blanks and get the job done… the Infantry couldn’t do that.

As for the repeater stations themselves, except for the lack of electricity to keep them running, it was generally found that the North Koreans left them alone. Because of this, when the 71st arrived most repeater stations were found in good shape if not operational. That is, all except for the one at Kumchon. At Kumchon the entire station had been leveled by artillery fire. Fortunately, someone in the Signal Corps, realizing that Japan had built the repeater stations to begin with, took the time to contract the Japanese to build a few more… but this time using U.S. equipment and a U.S. design, and in Army vans and trailers located back in Japan. Since this work began almost as soon as the war itself began, when Kumchon was found out of action there was a replacement already waiting to be slotted into position, sitting back behind the Infantry, only a few miles in the rear of the front line.[3]

How did they do this? Going back to our trifecta of brains, brawn and assets, as soon as each Japanese repeater van/trailer was completed and tested it was airlifted to Korea, where it was brought up the road and positioned only a few clicks behind the line. This allowed the assets to be where they were needed, when they were needed. In terms of what a 'repeater station van' held in the way of equipment, they came in three versions, known as CF-1, CF-2 and CF-3. The CF-1 van held telephone terminals, CF-2 held telegraph terminals, and CF-3 held the repeaters themselves.

Overall, what the Signal Corps and Captain Striley—a U.S. Army Signal Corps OCS graduate—did was keep the absolutely essential Mukden Cable online, operating and working… right there, on the heels of the advancing Infantry.

Our salute to Captain Striley and his men… HOOAH!

 

            

Footnotes

[1] Japanese publication: Nichi-Man renraku denwa koji shunkosu; TKZ 375, November 1939, pages 120-126. To return to your place in the text click here:

[2] Captain Striley was from Indiana. He passed away in January 2009.  - To return to your place in the text click here:

[3] The only loss in capability between the Japanese design and the U.S. design was that the U.S. repeaters were only able to provide four circuits from each quad instead of six. In the end however, this was because of the type of circuit design employed so that standard U.S. equipment could be used. - To return to your place in the text click here:

Additional Sources

Technology of Empire: Telecommunications and Japanese Expansion in Asia, 1883-1945, Daqing Yang

Various online published remberances of Captain Wayne A. Striley .

Watching the Sun Rise: Australian Reporting of Japan, 1931 to the Fall of Singapore, Jacqui Murray

Military Communications: From Ancient Times to the 21st Century, Christopher H. Sterling.

 

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This page originally posted 11 Mayy 2014