United States , California, 1935 In 1935, the Army ordered an additional 103 aircraft designated
B-10B. These had only minor changes from the YB-10. Shipments began in July
1935. B-10Bs served with the
2d Bomb Group at
Langley Field, the
9th Bomb Group at
Mitchel Field, the
19th Bomb Group at
March Field, the
6th Composite Group in the
Panama Canal Zone, and the 4th Composite Group in the
Philippines. In addition to conventional duties in the bomber role, some modified YB-10s and B-12As were operated for a time on large twin floats for coastal patrol. In February 1936, the US Army Air Corps used 13 B-10Bs of the
49th Bomb Squadron to drop supplies to the residents of
Virginia's
Tangier Island and
Maryland's
Smith Island; with ships unable to reach the islands due to heavy ice in the
Chesapeake Bay, the islanders faced starvation after a severe winter storm. The B-10B supply flights followed earlier supply flights to the islands by the
Goodyear Blimp Enterprise on 2 February 1936 and by the squadron's
Keystone B-6A bombers on 9 and 10 February 1936. With its advanced performance, the Martin company fully expected that export orders for the B-10 would flood in. The U.S. Army owned the rights to the Model 139 design. Once the Army's orders had been filled in 1936, Martin received permission to export Model 139s, and delivered versions to several air forces. These included six Model 139Ws sold to
Siam in April 1937, powered by
Wright R-1820-G3 Cyclone engines, and 20 Model 139Ws sold to
Turkey in September 1937, powered by R-1820-G2 engines.
China In July 1936, the Martin B-10 was put up for export, with the first sale being made to the
Republic of China Air Force in the same year, purchasing six Model 139WC-1s and three Model 139WC-2s. When introduced, it was the fastest aircraft in China. The 139WC was primarily used for
night bombing and
maritime reconnaissance. On 25 August 1937, as the air battles intensified in the early part of the
Second Sino-Japanese War, five
Chinese Nationalist Air Force bombers of the
8th BG, 19th and 30th Squadrons consisting of three
Heinkel He 111As and two Martin B-10s, flying from their base in
Nanjing to
Shanghai, successfully dropped their bombs on Japanese landing forces at
Liuhe, Taicang, northwest of Shanghai. However, Japanese aircraft pursued the bombers and shot up two of the Heinkels, forcing them to crash land; two crew members were killed on the ground by Japanese aircraft strafing them. As the
National Revolutionary Army of China fought desperately to hold onto their remaining positions in the
Battle of Shanghai, the Chinese Air Force launched a major strike with a motley mix of aircraft against Japanese positions in Shanghai on 14 October 1937, consisting of three B-10s, two Heinkel He 111As, five
Douglas O-2MCs, five
Northrop Gammas, and three
Curtiss Hawk IIIs from Nanjing in the late afternoon; in the evening, one bomber was launched every hour from Nanjing to attack Japanese positions in Shanghai until 03:00 on 15 October. On 19 May 1938, two B-10s of the
2nd BG, 14th Squadron, led by Capt.
Hsu Huan-sheng and Lt. Teng Yen-bo, successfully flew the first air raid on mainland Japan; the unescorted nighttime raid over Japan saw the B-10s dropped 2 million leaflets in "alerting the conscience of the Japanese people against atrocities committed by the Japanese invasion and occupation of China", over the cities of Nagasaki, Fukuoka, Kurume, Saga, and others, while reconnoitering airbases, ports, warships and factories.
Dutch East Indies In the mid-1930s, the Netherlands government adopted a doctrine for defense of the
Netherlands East Indies, which relied on the use of land-based bombers against any attacking force, with orders for defensive fighters cancelled to pay for the bomber force. The Martin 139 was chosen in preference to the Dutch
Fokker T.V, as its all metal construction was considered more robust than the steel tube and fabric Fokker, while the Martin bomber was also already in production and therefore would be available sooner. Twelve Martin 139 WH-1s were ordered for the
Royal Netherlands East Indies Army Air Force (ML-KNIL) in 1936, followed by 26 improved WH-2s in March 1937, sufficient bombers to equip a Group of three squadrons. In December 1937, an order was placed for 39 Martin 139 WH-3s, followed by an order for 40 Martin 139 WH-3As in November 1938. Two more Martin 139 WH-3As were ordered in July 1939 to replace aircraft lost during delivery. The last of these attrition replacement aircraft was delivered in March 1940, including the last Martin B-10/139 built. On the outbreak of war with Japan in December 1941, about 58 Martins (WH-3 and WH-3As) were operational with six squadrons, with about 20 more of the older variants in reserve. B-10s of the ML-KNIL served in the
defense of the Dutch East Indies. During the start of
Pacific War, Dutch Martin units were as follows: •
Ie Vliegtuiggroep (VLG-I) based on
Andir Airfield,
Bandoeng which consisted of
1e Afdeling (1-VLG-I) and
2e Afdeling (2-VLG-I), each has nine Martin 139WH-3/3A with additional two aircraft as reserve. Each
afdeling has a detachment during the war, with the
Patrouille Butner of 1-VLG-I stationed at
Tarakan and
Patrouille Cooke of 2-VLG-I stationed at
Samarinda II Airfield,
Melak. •
IIe Vliegtuiggroep (VLG-II) based on
Singosari Airfield,
Malang which consisted of
1e Afdeling (1-VLG-II) with nine WH-3/3A with three additional reserves and three WH-2. During the war, four
patrouille consisted of three aircraft plus a reserve were created from 1-VLG-II, with the crews mobilized from
Kalidjati flight school. •
IIIe Vliegtuiggroep (VLG-III) based on
Tjililitan Airfield,
Batavia which consisted of
1e Afdeling (1-VLG-III) and
3e Afdeling (3-VLG-III), each equipped with nine WH-3/3A with two additional reserves, and
2e Afdeling (2-VLG-III) with nine WH-2 with two additional reserves.
7e Afdeling Bommenwerpers, a reserve unit mobilized on 15 December 1941, were placed under VLG-III and consisted of one WH-2, two WH-3 and six WH-3A.
Malayan campaign In efforts to reinforce the British defense of the Malay Peninsula, the Dutch East Indies sent some ML-KNIL squadrons. Included were 22 Martin 139s from VLG-III that were organized into three squadrons, which arrived at Singapore on 9 December 1941. Due to a lack of coordination, British AA mistook the Dutch Martins for enemy aircraft and engaged them as they neared Singapore. The Martins were then stationed at
Sembawang. In early January 1942, Dutch Martins along with British
Blenheim bombers sortied over the west coast of Malaya to halt the Japanese advance. On 8 January, nine Martin and four Australian
Hudson attacked a suspected Japanese seaplane tender anchored offshore in South China Sea, but the results were inconclusive. In the next day, nine Martin "quite successfully" bombed several Japanese ships unloading cargo at
Kuantan. Two Martins were shot down by the Japanese near
Penang on 1 January, while a further four Martins were lost while attacking Japanese forces on the
Muar River on 19 January. On the same day, Dutch fighter squadrons were withdrawn to Sumatra, while the Martins were also withdrawn to Java three days later. Additional two Martins were destroyed and another two were damaged during an air raid at Sembawang on 22 January.
Dutch East Indies campaign From 16 to 20 December 1941, Dutch Martins based at
Singkawang and
Samarinda launched attacks against Japanese invasion fleet and shipping off
Miri,
British Borneo. One Martin bomber was shot down by
F1M "Pete" floatplanes from on 19 December, and a total of three Martins were destroyed by Japanese raids against Singkawang II airfield on 22 and 24 December. The Martins sank a transport ship and the minesweeper
W-6 off
Kuching on 26 December.
Thailand Six B-10s formed the medium bomber force of the
Royal Thai Air Force at the start of the 1940–1941
Franco-Thai War. with the last mission, against
Sisophon in what is now Cambodia on 28 January at the very end of the Franco-Thai War. Later on, B-10s had been assigned to the airfield in Phrae as a part of Phayap Army to invade Shan state.
Turkey After being delivered in September 1937, the Martin 139WTs were assigned to the 55th and 56th Tayyare Bölüğü (Aviation Squadrons) of the 9th Tayyare Taburu (Aviation Battalion). During the
Second World War, the aircraft were extensively deployed for surveillance over the
Black Sea. After being replaced by British Blenheims and Beauforts in 1944, the Martin 139WTs served as backup aircraft until 1946, when twelve of the sixteen remaining aircraft were still operational. ==Legacy==