On 7th July 1937 Japan invaded China sparkling the Second Sino-Japanese War. The Chinese Air Force (CAF) had, at that time just 284 aircraft and was commanded by General Moa Pang-chu who had learned to fly in the USSR.
On 21st August both China and the USSR signed a non aggression pact, by virtue of which a secret clause was included to send military aid to China. This clause stressed on rebuilding the virtually destroyed Chinese Air Force. The Chinese negotiated a major loan with the USSR to provide China with war materials in exchange for cheap raw resources over the next five years.
During the course of October 1937, four hundred fifty Soviet pilots and technicians were gathered at Alma Ata (Kazakh SSSR - nowadays Kazakhstan) from where they departed with a first batch of 185 aircraft (115 fighters, 62 bombers and 8 advanced trainers). These aircraft were transported by rail from Alma Ata to Lanzhou (province of Gansu) , where the Chinese railroad ended, following the trace of the old Silk Road.
Chinese SB 2M-100-As (with old style cowlings) were all built at the GAZ factory No. 125 Imeni Stalina located at Irkutsk, in Siberia. Soviet pilots collected the first batch of bombers from the factory and ferried them from Irkutsk to Suzhou (in Gansu too) via Ulan Bator, Mongolia. Due to a sandstorm, the aircraft had to be grounded for a short time, before resuming the flight from Suzhou to Lanzhou. Many Soviet advisors began to train Chinese crews assigned to the 2nd Group of the CAF, on the SB 2M-100A. The first combat mission was led by Cpt. I.N. Kozlov on 2nd December 1937, when nine SBs attacked Japanese shipping in the East China Sea off the coast of Shanghai.
A second batch of 31 SB 2M-100A was led by Cpt. Fiodor P. Polynin. These machines were ferried from Irkutsk to Hankou with stopovers at Ürümqi (Xinjiang), Hami (Xinjiang) and Lanzhou. The bombers were manned by Soviet crews until the Chinese were able to master the aircraft. A total of 150 sorties were flown by Soviet volunteers against Japanese airfields, riverine traffic and communications centers during the months of January and February 1938. One such mission took place on 25th January 1938 when 13 SB 2M-100A attacked the Japanese airfield at Nanjing (Jiangsu).
On 23rd February Cpt. Polynin led a force composed of 28 SB 2M-100As to attack the airfield of Hsinchu, at north-western Formosa (Taiwan). The bombers were armed with ten bombs each and flew most of the distance from Lanzhou to Formosa across it straight at 5.500 m (18.045 ft) of altitude, causing headaches to crew members due to the lack of oxygen. In spite of this problem, the SBs approached Hsinchu from the north achieving total surprise when they dropped their bombs. Japanese anti-air fire proved ineffective and no Japanese fighters were put in the air to intercept the bombers. The SBs arrived back at Lanzhou without any incident after a seven-hour mission. Madame Chiang kai-shek, wife of the Chinese leader, rewarded the Soviet airmen with a banquet and decorations.
All those previously mentioned missions were flown without fighter escort, as the SB 2M-100A was the fastest bomber present on both sides of the Second Sino-Japanese War. These bombers suffered relatively low losses during combat and the biggest threat to them were Japanese raids on SB airfields.
A third Soviet bomber group (the exact number of flown aircraft is unknown) led by Georgy I. Tkhor left GAZ 125 at Irkutsk in late April 1938 and ferried to Lanzhou, this time via Ulan Bator and Dalanzadgad (Mongolia). This group took also part in many missions against the Japanese between the months of June and October 1938.
In late 1939 several SB 2M-103 were also supplied to the CAF. It was at this time when Soviet volunteer airmen began to leave China, as the Soviets became disillusioned and frustrated in spite of the fact that Soviet aid help to strength Chinese resistance against the Japanese. The Soviet aircraft were often misused and crashed when manned by Chinese crews as they lacked experience and therefore didn't follow (or didn't understand) Soviet instructions. The Chinese put the SBs in reserve, instead of flying them into combat.
On 27th December 1939 three SB M-103 of the last Soviet volunteer unit at Hengyang (province of Hunan) flew southwest to support Chinese ground troops at the Battle of Kunlun Pass. They were escorted by the last Gloster Gladiator fighters of 28th Squadron. After the Soviet withdrawal the remaining SB 2M-103s were assigned to the 1st and 2nd Groups of the CAF.
In 1940 a single Tupolev SB constituted the only offensive aircraft the Collaborationist Chinese Army Air Force (CCAAF - AKA Peacebuilding National Army) had. It was joined in September by another SB, piloted by Cpt. Zhang Diqin and manned by Lts. Tang Houlian and Liang Wenhua who defected to Nanjing, and were given substantial reward by the Japanese.
Chinese-manned SBs suffered heavy losses against experimented Japanese pilots. The USSR supplied 100 SB 2M-03 (including some SB 2M-105 -which was one of the last production variant-) in early 1941. These replaced some of the aircraft lost the previous years to accidents and combat. China became the largest foreign user of the SB with a total of 392 aircraft delivered straight from Soviet production lines. On 13th April 1941 Stalin and Japanese foreign minister Yosuke Matsuoka signed a neutrality pact. This resulted in a swift halt in the deliverance of Soviet war material to China, but the SBs were allowed to remain in CAF service. A formation of three SB 2M-103s made three attacks on Japanese troops crossing Dongting Lake (Hunan) and raided Yichang (province of Hubei) in September 1941.
Chinese SB 2M-103 served well into 1943 and, in some missions, they were escorted by the Curtiss P-40 of the American Volunteer Group, the famous Flying Tigers.
Apparently some few SB survived World War 2 and took part, albeit in limited number and usage, in the last stage of the Chinese Civil War (1945-1949).
Sources:
Sources:
1st Signal Squadron - Aircraft In action 194 - Tupolev SB in Action
2nd https://en.wikipedia.org/wiki/Tupolev_SB
3rd https://massimotessitori.altervista.org/sovietwarplanes/pages/sb/tapani/chinese/chinese.htm
