Operation Portrex


22 SEPT 93

Intelligence, deception, and unorthodox stay-behind operations in a combined and all but real-war combat exercise.


Edwin L. Sibert

There used to be some truth in the gibe that a war's first battles are fought with the weapons and techniques (including intelligence techniques) of the final engagements of the last previous war. Now, however, the practice of conducting large-scale and realistic maneuvers in time of peace, incorporating new developments not only in weapons and tactics but also in intelligence, psychological, and paramilitary devices, provides assurance that the first battles of the next war will at least be fought with the methods of the last maneuvers. One such war game in which I participated during the military doldrums between World War II and the Korean War was a particularly stimulating illustration of how realistic an exercise can be made, of some practical limitations on realism, and of the extent to which deception and unconventional operations can be worked in.

Operation Portrex wasn't so very big, as modern maneuvers go, but all elements of the armed forces--Army, Navy, Air Force, Marines--took part, and there were paratroopers, frogmen, undercover agents, and guerrillas. It was staged in the first quarter of 1950 on the island of Vieques, a twenty-mile stretch of land some ten miles east of Puerto Rico. It embraced a period of more than two months devoted to preparations for a three-day assault action.

The problem of the exercise was the recapture of a hypothetical major Caribbean island which the enemy had occupied. U.S. forces were to make a combined airborne and amphibious assault on its southern beaches, represented by those of Vieques, and clean out the ten-square-mile maneuver area on this island in the initial action. The cards were stacked against the enemy defenders, who had available in the beach area only a regimental combat team reinforced by a provisional armored reconnaissance unit, an engineer company, and a mixed battalion of anti-aircraft artillery, with light aviation and the support of a weak fighter wing. The invading task force consisted of the 3d Infantry Division reinforced by a battalion of the 82nd Airborne Division and a Marine Corps reconnaissance company. It had the support of a strong fighter wing based on Puerto Rico, air lift for the parachute battalion, adequate sea lift for the ground forces, and naval units for shore bombardment.



(Refer to Hard Copy for Image)

I commanded the land forces of the enemy defense, Puerto Rican regulars. In mid-December 1949 I was permitted to take them to Vieques. First we had to construct a tent camp for ourselves and the numerous visitors expected, both VIP's and run-of-the-mine; but by New Year's we were able to turn our attention to defensive works--obstacles, strongpoints, camouflage, protection against shell fire and air bombardment, deception, counterespionage, and unorthodox measures.


Defenses and Deception

The beaches called Red and Blue on the accompanying map were the major ones, the only ones big enough to accommodate a regimental combat team. But since an envelopment of our east flank was indicated by the geography of the maneuver area, we had to construct obstacles and defenses not only on these but also, less thoroughly, on the small and shallow Yellow and Green beaches. Materials and supplies might have been a problem. Vieques Island has a population of only about two thousand, mostly small farmers and poultry and cattle raisers, concentrated in a restricted central area. Its east and west ends are uninhabited training grounds. Its only town is Isabela Segunda, with one street, unpaved. Therefore all our ordinary supplies and all materials for defensive works had to come from the San Juan area in Puerto Rico by tug and barge.

Fortunately we had a sizable salvage yard at Fort Buchanan, Puerto Rico, with a wide assortment of war surplus items such as steel landing mats, I-beams and other odds and ends of structural steel, old cable, etc. These, interspersed with felled cocoanut palm trunks and thoroughly laced with barbed wire, made formidable abatis-type obstacles. We also bulldozed out anti-tank ditches at strategic locations; and we supplemented our limited allotment of barbed wire and screw-type steel posts for apron fences by stuffing in among them a lot of the heavy, thorny, tough brush that was prevalent in the area. I'm sure our post-maneuver popularity with the invading troops was of a low order.

Back from the beaches we burrowed as no one had since World War I, and we found that in that tropical, rain-drenched country you had to drain a ditch or dugout before it could be used. In one of the necessary departures from complete realism, we were ordered to clear all the stumps, stakes, stones, etc., from a large flat area around the airstrip behind Red beach, an obvious tip-off that this would be the drop zone for the parachute troops.  I saw to it that this work was done most conscientiously: my son commanded a company in the airborne infantry battalion attached to the 3rd Division.

As we were building the defenses during January and February, the invaders were regularly taking air photographs on which to base their assault plans. In order to throw them off, we used not only camouflage but an elaborate system of dummy defenses ostensibly disposed against an expected main thrust of the invading forces north from Blue beach. These were strongpoints of ground scraped up by the bulldozers, protected by piled thorny brush, and equipped with inflated tanks and dummy guns, trucks, and communications equipment. The so-called Aggressor Cadre from Fort Riley furnished this dummy equipment and helped greatly in the deception work.

Trying to find some way to misguide the leading assault waves of landing craft, we conceived the plan of camouflaging the principal small-scale landmark in the area, an old two-story Spanish lighthouse west of the beaches, and erecting a false facsimile about a mile away. I knew our engineer, Jim Goodwin, could do it, because he could make anything; but I was forethoughtful enough about my eventual retirement pension to ask the Naval District Commandant's advice in the matter. Seldom have I seen a man so shocked; his voice shook with emotion as he dwelt on the sacredness of aids to navigation. So we had to call that off. I finally got permission to use a smoke-screen, under the proviso that it be lifted ten minutes before the landing craft were to touch down.

A particular tricky detail in our defenses was our use of the small island that the map shows about 600 yards off Blue beach, a low and rocky one accessible by rowboat but not by landing craft. We were careful that air photographs should show us ignoring its potential as a defensive strongpoint, but we dug at its north end and heavily camouflaged a deep shelter for .50-caliber machine guns sited to fire on the beach. They were to wait until the landing craft had touched down and then open fire on the invaders from the rear; in the noise and confusion of the landing it would be some time before their fire would be identified and located, not to say suppressed.


CI, PP, and PM Preparations

Our attention was by no means all on hardware. We took advantage of the Puerto Rican troops' capability in Spanish to have them use it exclusively whenever there was a possibility that the American enemy would intercept their communications. We elaborated their natural difference in appearance from the U.S. forces by giving them a distinctive helmet and fatigue clothes dyed green, items provided by the Aggressor Cadre. We issued them identity folders, printed by the Aggressor Cadre. which served us as a counterespionage device and which the invaders later used as a basis for PW interrogations.

For the benefit of the enemy we put up a lot of posters with warnings about non-existent dangerous snakes and insects, as well as some existing poisonous tropical plants like the manzanillo. Our psywar effort may have been a bit on the light side though; the "1984" motif was strung through all our propaganda, and some wag even put a huge "Big Brother Is Watching You" sign up in the latrine we erected for female VIP visitors, correspondents and the WAC and WAF brass.

But the most important thing I did with respect to unconventional measures was to persuade Waller Booth, a former OSS officer living in San Juan, to come on active duty for the exercises. It was he who organized and directed an undercover net of counterespionage agents among the native residents of Vieques and who prepared a group of stay-behind guerrillas to operate within the invaders' beachhead.

About half a mile inland between Red and Blue beaches lay a heavily wooded swamp perhaps a mile in diameter, where the ground stood generally under two or three feet of water. Booth picked this place as his homey hideout for a motley crew of about sixty stay-behinds carefully selected for a variety of virtues, some of them dubious. He built a wooden walkway about six inches under water into the center of the swamp, marking its location with cryptic blazings on the trees. Here he erected above water a shelter with crude sleeping and eating facilities, storage space for supplies, and a communications center connected by hidden telephone lines to our main switchboard. The hideout was invulnerable to air photography and not a likely target for naval gunfire. Booth stocked it with rations, water, weapons, ammunition, and demolition material sufficient for the entire period of the maneuver. His men wore enemy uniforms.

Booth's other enterprise, the counterespionage net, showed its effectiveness as D day approached. Our security vigilantes picked up two enemy agents in Isabela Segunda, CIC men in civilian clothes posing as commercial travelers from San Juan, before they had been able to get into the defense area or send out any message. No agent ever penetrated the maneuver area.

On the two nights before D day at least a hundred enemy frogmen swarmed in to reconnoiter the beaches, but they failed to detect the machine gun nest we had hidden on the island off Blue beach. Our defenses looked from the air so formidable, however, that on D minus 1 we were ordered to detonate 100-lb. static charges of TNT among the obstacles to simulate the effects of naval bombardment. Jim Goodwin had a long and eloquent discussion with the umpires about the number and position of these detonations, and in the end they did surprisingly little damage.


The Action

On D day, the attack made a fine show coming in.  But it was stopped cold by our smoke-screen, borne on a steady trade wind blowing ideally from just north of east, until we were forced to lift it at the stipulated time.  Then it was hard, slow work for the invaders to carve a foothold on the main beaches, and our machine gunners on the island off Blue beach wreaked great theoretical slaughter before their ammunition was exhausted.

Shortly after the amphibious touch-down the airborne troops were dropped in the expected area. I'll never forget the awesome beauty of those thousand parachutes opening white against the clear blue tropical sky, accented by the brilliant colors of the cargo chutes. But the airborne assault, which was supposed to link up rapidly with the other forces and proceed to wipe out the shattered defenders, was a failure. The twenty-mile-an-hour trade wind was rough on the jumpers; although there were no fatalities, some ninety men were hospitalized. The seaborne forces were so delayed by our obstacles that they couldn't come to the aid of the paratroopers, and we captured most of them. I was relieved to see my son walking around in the PW enclosure, and proud that he refused to accept a can of beer from me unless all the prisoners in the enclosure were similarly favored.

We also took prisoner the Marine Corps reconnaissance company, which had been assigned the job of protecting the invaders' east flank where our defenses were weak. We offered the Marines no opposition until they got so far inland that they were out of touch with the main forces and had exhausted their fuel and ammunition. Their capture left the enemy flank wide open to anti-tank fire and counterattack from our anti-aircraft and reserve infantry battalion operating outside the envelopment.

Along about noon of D day, at the expense of many hundreds of theoretical casualties, the main invading forces had fought their way inland past the swamp hideout of Booth's guerrillas, who now began to trickle out and mingle in their American uniforms with the enemy on the beachhead, where all of course was confusion. For the next three days, operating mostly at night, they performed all the functions of a real fifth column, with which the Army, Navy, Air Force, and Marine invaders were completely unprepared to cope. Their most valuable contribution was a steady flow of intelligence to our headquarters, but some of their paramilitary exploits were more spectacular.

They put time-fused incendiary bombs in all manner of dumps along the beaches and on board beached LST's. They placed shaped charges against a cruiser lying off shore. They captured and used an enemy tank. They theoretically killed the enemy Corps and Division Commanders by simply knocking on their tent poles, handing each a musette bag "from Colonel so-and-so," saluting, and disappearing: the bags held simulated bombs timed for something like thirty seconds. They captured officers carrying communications instructions for directing field artillery and naval gun fire, data which by the end of the maneuver had almost got us, the defenders, accepted into the invaders' naval gun radio net, and had actually enabled us to make the enemy field artillery fire in places of our own choosing.1

In spite of his set-backs and losses, the invader succeeded, using a clever night operation which had been rehearsed at Fort Benning, in gaining a lodgment on VIP hill by about midnight after D day.2 Having intelligence of his strength and fearing that morning would find us in a precarious position, I ordered at 0200 hours that an over-all withdrawal to our second position be completed before daylight. This was a large order, but it worked: dawn on D plus 1 found the enemy coming out of his corner punching wildly in the air, that is deluging our now empty old positions with a heavy artillery barrage. That day and the next we made two successful surprise counterattacks, and when the problem was called off at 0900 on D plus 3 we were still an organized force with a small reserve at hand.

Wally Booth stayed on in the service after the maneuvers, and in 1952 he was wounded while engaged in guerrilla activities on an island off the eastern coast of North Korea. I am told that one result from our efforts at Vieques was the establishment of an Army school to teach the kind of operations Wally demonstrated there. If that is true, one of the buildings at the school should be called Booth Hall.

1 That these small off-beat operations can sometimes yield disproportionate results was brought home to me again later, in Korea during the last Red push in the summer of 1953. In the Seoul-Inchon area a couple of light enemy aircraft were making a series of inconsequential night-time intrusions, flying low so they were almost impossible to intercept. Since they did little or no damage, however, they were shrugged off and left to the quadruple mounted .50-caliber machine guns posted throughout the area. At Inchon one of these gun posts, sandbagged on a knoll, guarded a great dump of oil in 55-gallon drums, fuel which would be needed by our forces in opposing the current large-scale enemy offensive.  One night, as one of the light intruder planes, flying low in the usual pattern, came over toward this dump, enemy agents by sniping drove the gun crew momentarily from their post. The plane dumped a sackful of incendiary grenades into the acres of piled-up oil drums, and the fat was in the fire. Only the depot commander's precaution of having stacked the drums in well-separated small piles and his prompt action in containing the fire saved us from a critical fuel shortage at a critical time. A silly little operation, one that could probably never be repeated, had come close to having very embarrassing results.

2 The battalion commander in this action was Lt. Col. Joe Stillwell, Jr., now a general officer.


Historical Document
Posted: May 08, 2007 07:26 AM
Last Updated: Jul 01, 2008 10:12 AM