By now, though, three small Soviet gunboats had arrived on the scene, and on June 30 Japanese Kwantung Army forces opened fire, sinking one boat and damaging another; thirty-seven Soviet sailors died. Disgust at Tokyo’s “timidity” and an urge to respond to the Soviet “buildup” were strong. Stalin had a diplomatic protest lodged, but he refrained from military retaliation. Japanese intelligence intercepted Blyukher’s order from Khabarovsk to the Amur flotilla commander to withdraw. On July 3—the same day Yezhov’s NKVD order went out to branches to prepare for “mass operations” against the USSR’s own population—Soviet troops began to evacuate the islets. Manchukuo filled the vacuum on July 6, occupying the now evacuated (and until recently unoccupied) islets and converting Kanchazu into de facto Manchukuo territory, which still drew no Soviet response. Japanese intelligence could scarcely believe the near hysteria in intercepted Soviet military communications: a few artillery rounds seemed to have frightened the Red Army away, despite its three-to-one troop advantage in theater. “I think it was a really good ‘reconnaissance’ in force,” a Japanese intelligence officer concluded of the unplanned skirmish. Thus, while the Amur incident had persuaded much of the Kwantung Army of Tokyo’s timidity, the general staff in Tokyo had begun to discuss the hollowness of the Red Army.143
Japanese troops (numbering between 5,000 and 7,000) also controlled all the areas of China immediately north, east, and west of Peking—areas that faced the USSR and the Soviet satellite of Mongolia. On July 7, 1937, about 135 of those troops were engaged in night maneuvers ten miles west of Peking at the Marco Polo Bridge, an 800-year-old ancient granite structure once restored by the great Qing emperor Kangxi. The bridge, near a railway choke point, had long been coveted by Japan, because it served as the sole link between Peking and the rest of Nationalist-controlled China. Unusually, these Japanese night maneuvers took place without prior courtesy notice, and around 10:30 p.m., Chinese troops, perhaps fearing that an actual attack had commenced, fired some rifle shots. The Japanese returned fire. After mutual apologies for the minor firefight by the two sides’ liaison officers on duty, as well as some bellicose statements, the Japanese brigade commander refused to back down and ordered an artillery barrage. The Chinese shelled the Japanese in return. Then, on July 9, the Japanese and Chinese commanders in the Marco Polo Bridge area agreed to a cease-fire and mutual pullback.
Chiang Kai-shek was at Lushan for a military conference and, on the basis of radio reports, could not judge whether the gunfire and shelling had been unplanned or constituted a Japanese provocation, on the order of the Mukden incident that had preceded the seizure of Manchuria. He felt constrained to deploy some of his best divisions, institute martial law, and order a general mobilization. Japan’s government, now headed by prime minister Prince Fumimaro Konoe, deemed the incident a Chinese “provocation” and dispatched three divisions. When the Japanese troops arrived at Tientsin, on July 12, Chiang telegrammed his military in the field: “I am now determined to declare war on Japan.”144 On July 22, the Japanese commander at the Marco Polo Bridge announced a deadline for Chinese troop withdrawal; Chiang ordered his men to attack. Few in the Konoe cabinet were for all-out war, but few were against it. Tokyo announced, to popular acclamation, that it had been “forced to resort to resolute action.”145 With Emperor Hirohito’s approval, the Japanese bombarded and seized Peking (July 28) and nearby Tientsin (July 30).146
Stalin was saved. His insistence on a “united front,” instead of an attempted Communist takeover, now looked prescient, but he had to weigh continuing support for the anti-Japanese resistance in China against possibly provoking Japan into war against the Soviet Union. The Soviet department in Japanese military intelligence had correctly surmised that Moscow would not intervene in the event of a Japanese expedition to Peking.147