The China theater posed unique problems for the U.S. military. Unlike Western Europe, where key partners employed comparable resources, operations in China involved only a handful of U.S. ground and logistical units in support of huge Chinese armies. Moreover, civil strife in China, which long predated the outbreak of World War II and was, at best, only obscured by the struggle with Imperial Japan, made any conventional approach to American support unrealistic. Within both the Nationalist Chinese and Red Chinese armies, internal politics and military reform were inextricably linked, and any hope of creating an effective and conventional Chinese military while temporarily shelving China's internal political problems was unrealistic.
The U.S. Army's main role in China was to keep China in the war through the provision of advice and materiel assistance. As long as China stayed in the war, hundreds of thousands of imperial Japanese Army soldiers could be tied down on the Asian mainland. Success was thus measured differently than in most theaters. How well both General Stilwell and General Wedemeyer persuaded the theater commander-in-chief, Generalissimo Chiang, to support U.S. strategic goals, and how effectively U.S. training and materiel support could build selected Chinese Army divisions into modern tactical units, capable of standing up to Japanese adversaries, were secondary objectives. What mattered most was simply keeping China in the war against Japan.
The major U.S. failure in China was logistical: America was not able to meet its lend-lease commitments. The closing of the Burma Road in 1942 made it impossible to deliver sufficient equipment, weapons, and munitions to build the dream of a well-equipped and trained thirty-division Chinese force. By the time the Burma Road reopened and supplies flowed freely across the border into China, operations in other theaters had shaped the course of the war against Japan. A paucity of available airlift capacity meant that deliveries of supplies to China over the Hump proved barely adequate to replace Chinese war losses, but not to sustain a major unit modernization and training program. Generalissimo Chiang used this U.S. failure to undermine General Stilwell's credibility in Chungking and to reject his strategic and operational guidance when it conflicted with the Generalissimo's desires.
The political nature of the Nationalist Chinese Army threatened all American objectives in the China theater. Since that army served primarily as a political tool of Chiang Kai-shek and as a foundation of the Nationalist regime, any action that modified its structure or risked its destruction was assiduously avoided by the Nationalist government. The army had to be maintained, not reformed. Military commanders were selected for their political loyalty to Chiang rather than for their military ability, and risking excessive casualties through offensive operations was unacceptable. Chiang also had to keep his Communist rivals at bay, habitually using his best troops for that purpose. Combined operations by rival Chinese armies against the Japanese were impossible. Thus, differing Sino-American aims, magnified by internal political conflict, cultural differences, and the personality conflicts between General Stilwell and Generalissimo Chiang, all inhibited chances for success in the war effort.
Both Stilwell and Wedemeyer found themselves involved in competing priorities between the air and ground wars. Although he recognized the value of the support of the Fourteenth Air Force to the Chinese Army, Stilwell was increasingly frustrated by Chennault's success in selling his ambitious air campaign. Chennault had secured President Roosevelt's support by promising a quick, cheap victory through air power that avoided relying on the problem-ridden Chinese Army. The thought of using Chinese air bases for U.S. planes to attack Japanese bases in China, Japanese shipping in the Pacific, and Japan itself had tremendous appeal to the president. The same concept appealed to Chiang because it required few of his precious resources. In contrast, the plans of Stilwell and Wedemeyer demanded the "Americanization" of theater operations and a major overhaul of the Chinese Army. Ironically, for political rather than military reasons, Chennault's request for diversion of Hump supply tonnage and coolie laborers to build air bases was perhaps the more practicable course of action.
Despite these problems, the China Defensive Campaign succeeded. China remained in the war, diverting 600,000 to 800,000 Japanese troops, who might otherwise have been deployed to the Pacific. Because of U.S. support to China, the Japanese Army might conduct limited offensive operations there, but had no hope of ultimate victory on the Asian continent. Chiang relied on his U.S. allies to open the Burma Road, and on U.S. air power to check Japanese offensives by interdicting supply lines in order to conserve his own army and the territory in the interior of China that his government continued to control. By May 1945, the United States and China were finally ready to assume the offensive in China.