Sink-On-Sight SINK-ON-SIGHT The normal submarine attack practice of stalking an enemy merchantmen and firing torpedoes without warning, and generally also without follow-up effort to tend to survivors See anti-submarine warfare; Athenia, sinking of; cruiser warfare; Dönitz, Karl; Laconia order; merchant marine; unrestricted submarine warfare; War Zones SINO-JAPANESE WAR (1937–1945) The first significant fighting between Japanese and Chinese armies took place in Manchuria following the Mukden incident (September 18, 1931) In January 1932, heavy fighting also broke out in and around Shanghai During the “Shanghai incident” ( January 28–March 3, 1932), many thousands of civilians were killed in heavy fighting in the city while nearly 250,000 refugees sought foreign protection in the International Settlement quarter The Japanese built up their ground forces until 50,000 Imperial Japanese Army troops relieved the initial group of a few thousand marines (Rikusentai) who were alone in the city in January Supported by carrier-based aircraft and a large IJN flotilla in the harbor, the Japanese Army attacked on February 19 The Chinese fell back as the Japanese threatened to encircle 19th Route Army, a force of about 30,000 of Jiang Jieshi’s best Guomindang troops The Japanese chose not to pursue, but remained in Shanghai in force In early 1933 the Japanese Guandong Army pushed into northeastern China from Manchuria, occupying Jehol province After heavy fighting, Jiang and the Guomindang, or Nationalists, agreed to the “Tanggu (Tangku) Truce” of May 31, 1933 In November 1935, a Guomindang army defeated a Japanese-sponsored Mongolian force that had been sent to split Mongolia from China and bring it instead under Japanese domination In 1936 Japanese troops made direct incursions into northern China, skirmishing and extending control of frontier zones Imperial General Headquarters in Tokyo committed to a conception of total war in this period that led to raw exploitation of northern China as critical to Japan’s imperial “defense.” The quixotic Xi’an incident temporarily reconciled Jiang and the Chinese Communists while also creating a broad Chinese–Manchurian alliance against the Japanese Chastened by his abduction and confinement at Xi’an, Jiang reluctantly sent some of his best Guomindang units north to defend Beijing: German-trained Central Army divisions Meanwhile, the Japanese reinforced their North China Garrison Army, drawing troops from Manchuria, Korea, and Japan Tension built through the spring and summer The critical moment came with a local border skirmish on July 7, 1937, the Marco Polo Bridge Incident The Japanese called it the “China Incident” (“Shina jihen”) Within weeks, that minor event was seized upon as a general casus belli by Japan By either name, highly aggressive and recklessly commanded Japanese forces assaulted northern China by the end of the month The cover for a larger war to conquer northern China took the form of complaints about Chinese mistreatment of Japanese nationals, ongoing boycotts of Japanese goods, and other economic grievances Eager to attack while the Red Army was being torn apart by Joseph Stalin’s blood purge, and further persuaded that military opposition would be weak and that the Chinese were politically divided, the Japanese struck on July 27 They 982