For the remainder of 1948, both sides consolidated their positions. The Viet Minh continued to train and equip their main forces in remote areas, to develop local militia and regional forces, and to establish political footholds in rural regions. Aided by their Navy, the French won or retained predominant influence in the heavily populated and strategically important delta and coastal regions of Vietnam. Notable successes were achieved in Cochin China, where Viet Minh actions resulted in the alienation of two strong religious sects—the Cao Dai, in the Tay Ninh Province area northwest of Saigon, and the Hoa Hao, in the region around Can Tho. The French exploited this situation by offering the sects substantial autonomy in return for a pledge to resist the Viet Minh. In Tonkin, strongly Catholic regions near Bui Chu and Phat Diem, which previously had attempted to maintain a perilous neutrality between the contenders in the war, began to swing to the French side.48

At the end of the year, the cruise of Arromanches showed again the major contributions aircraft carriers could make in a limited war. Arromanches, formerly HMS Colossus, a light carrier of British design, had been lent to France by the United Kingdom in August 1946 for a five-year period. With her full-load displacement of 18,000 tons, length of 695 feet, and speed of 25 knots, she was far better suited for combat operations than escort carrier Dixmude.

Making full use of her mobility during the short time on station, from 29 November 1948 to 4 January 1949, Arromanches and her obsolescent Dauntless aircraft carried out as many air support and strike sorties against the enemy as had been flown by the entire French Air Force in Indochina during all of 1948.49

Because of her mobility, the carrier was able to select launching and recovery points, thus avoiding adverse northeast monsoonal weather conditions which often grounded land-based air units. As United States forces would learn later, weather in Vietnam exerted a major influence on military actions, particularly air operations in the north. Late September is the beginning of the autumnal transition from the southeast to the northeast monsoon. Soon thereafter, cooling of the northern part of the vast continent

* O'Ballance, Indo-China War, pp. 83–92; Lessons of the War in Indochina, Vol. II, p. 17. "ONI, "French Naval and Air Operations in Indochina," The ONI Review, VI (Nov. 1951), p. 437; Mordal, Navy in Indochina pp. 284–91; Norman Polmar, Aircraft Carriers: A Graphic History of Carrier Aviation and Its Influence on World Events (Garden City, N.Y.: Doubleday and Co., 1967), pp. 564-67.

of Asia develops a wide, high-pressure area which increases in intensity. In the Northern Hemisphere, the air spirals clockwise out of the high pressure area. Although cold and dry at the source region over China, the northeast monsoon is greatly modified as it passes over the South China Sea and the Gulf of Tonkin, arriving over northern Vietnam as a warm, humid air mass. The result is increased rainfall and cloudiness east of the Annam mountains. This is the period of the Crachine, a phenomenon which occurs periodically until spring, generally persisting for two to five days at a time, with clouds 3,000 to 5,000-feet thick. Ceilings are usually below

1,000 feet and frequently below 500 feet. Often accompanied by fog and drizzle or light rain, visibility is generally reduced to less than two miles and frequently to less than a half-mile.

The transitional periods from late September to early November and from mid-March to mid-May are characterized by changeable weather, bringing frequent showers and thunderstorms as the zone of convergence between the two monsoons transits the area. In the summer, when heavy rains from the southwest monsoon are falling over the southern portion of Indochina, northern Vietnam enjoys its dry season.

Monsoonal weather also had an impact on naval operations along the coast, particularly in northern Annam and southern Tonkin, where high seas were produced by winds of the northeast monsoon sweeping across the full reach of the South China Sea. In addition to affecting French amphibious operations, seasonal weather influenced the introduction of Communist men and material into South Vietnam by sea, their movement from point to point along the coast, and the French efforts to prevent such operations.

Even without the problem of weather, the French Navy faced difficult problems in its maritime surveillance campaign. The legitimate activities of Vietnamese fishing and other small craft provided natural camouflage for the enemy's efforts to move men, arms, and supplies within Indochina, or to introduce these sinews of war from China. A French naval officer once related how, from a single point off the Annamese coast, he counted more than 500 small craft whose sails appeared to touch "each other," giving the appearance of a "white sea." The formidable problem, in these circumstances, was to identify which, if any, of the myriad of small craft were operating in the service of Ho Chi Minh.

"50

The task of interdiction was further complicated by effective Viet Minh control of a number of islands in the Gulf of Siam, coastal regions near Vinh in Tonkin, between Tourane and Nha Trang in Annam, and Cape Camau in Cochin China. Geographic factors compounded the problem, since the tortured coastline of much of Indochina offered numerous hiding places.

During the northeast monsoon season from October through March, the French considered the seas off the northern part of Indochina too rough to allow extensive waterborne traffic. During that time, naval leaders diverted their major attention to southern waters. When favorable weather

50

Quoted in Mordal, Navy in Indochina, p. 275; Hammer, Struggle for Indochina, p. 232.

returned to the north, the French shifted their patrol units to the coasts of northern Annam and Tonkin."

51

French ships and craft were placed under regional operational commands. For inshore and riverine activities, two of these commands were organized under the operational control of Commander Naval Forces (COMAR), Indochina and designated COMAR Tonkin and COMAR Mekong, the latter in the Cochin China region. Regional commands for offshore surveillance were established under Commander Naval Division, Far East. These were, SURMAR (a French acronym for Surveillance Maritime) Tonkin, covering the sector from the Chinese border to 18° north, and SURMAR Annam, which controlled the area extending from 18° north to 10°30′ north to the Thailand border.":

52

To increase the effectiveness of their maritime patrol efforts, the French established a third subordinate command, Commander Naval Aviation, under COMAR Indochina. The former was assigned land-based squadrons of Sea Otter observation aircraft and Catalina amphibian patrol planes, based near Saigon at Cat Lai and Tan Son Nhut respectively. Catalinas also were based near Haiphong at Cat Bi. Although used primarily for observation and coastal surveillance missions, the naval air units were under the operational control of the French Air Force commander in Indochina.53

The French were convinced that conducting small-scale amphibious raids against Viet Minh supply points along the coast was one effective means of interdicting the enemy's logistics. These operations resulted in a number of successes in destroying small enemy craft beached on the coast or the personnel facilities and supply depots that supported these units. Nevertheless, in their critique of the war, French officers noted that one of the frustrating aspects of such operations was the ability of the enemy to escape before contact was made. For this reason, French tacticians emphasized the need for the utmost speed of execution directly against predetermined locations of enemy forces. These authorities noted that encirclement tactics were

Mordal, Navy in Indochina, pp. 276-77.

52 NA Saigon, report. 1-S-50 of 21 Julv 1950, JN 11285, box 6, FRC; ONI. "French Naval and Air Operations in Indochina p. 431.

NA Saigon, report, 1-S-50 of 21 July 1950, JN 11285, box 6 FRC; Lessons of the War in Indochina, Vol. II, p. 336; Naval Section, "Area Report on Southeast Asia by the Military Group of the Joint Stare-Defense Survey Mission to Southeast Asia," 22 Nov. 1950, encl 8, p. 2 (hereafter cited as Melby-Erskine Report).

typically unproductive in the face of the enemy's skillful ability to avoid. combat when it was in their interest to do so.54

By the middle of of 1950, the French naval units involved in the war increased to approximately 165 ships and craft. French naval personnel totaled about 12,000, 10,000 of whom were assigned to the riverine, amphibious, and logistic components of COMAR Indochina. The seagoing forces included only 1 combatant ship of destroyer size or larger (a light cruiser) and 7 major auxiliary ships (1 transport; 2 oilers; 1 repair ship; 3 LSTS), with a carrier occasionally on the scene. The balance of the French forces was composed of patrol and landing craft, minesweeping units, and utility types. Approximately 40 of the landing craft, and a number of naval commando units were organized into 6 dinassauts, 4 of which operated in the delta regions of Cochin China and Cambodia and 2 in Tonkin.

55

A cruiser, 7 corvettes, 6 minesweepers, 2 escort ships, 3 launches, and 2 squadrons of naval observation aircraft had the formidable task of patrolling a coastline measuring approximately 1,500 nautical miles in length, an assignment that obviously could not be completely fulfilled without additional ships and inshore craft. Nevertheless, the French Navy reportedly achieved considerable success. Between 1,200 and 1,800 suspicious junks and sampans were hailed each quarter. Intelligence assessments indicated that Viet Minh infiltration by sea along the coast, by 1950, had been drastically reduced and perhaps eliminated in certain areas."

56

After three years, the first phase of the French-Viet Minh War was drawing to a close. During this time, naval power along the coast and on inland waters had made it possible for the French to make major progress toward winning the war. They had ejected the Communists from centers over which they had gained control at the start of the French-Viet Minh War. French forces had been reinserted in Tonkin and were increasingly extending their control in the populous delta and coastal regions.

On the other hand, as will be covered later, Communist successes in China and events elsewhere on the worldwide scene were already drastically changing the situation.

55

Lessons of the War in Indochina, Vol. II, pp. 185-87.

As calculated by Coast and Geodetic Survey using Base Line method.

Mordal, Navy in Indochina, pp. 277-83; ONI, "French Naval and Air Operations in Indochina," pp. 435-36.