B-18 Bolo walk aroundTotally inadequate for use as a frontline strategic bomber by the start of US involvement in WWII, the Bolo was still the most numerous American bomber at the time of Pearl Harbor, and several aircraft were destroyed during the strike on Hawaii and actions in the Philippines. This would be the closest the type would get to overseas action, and the Bolo was rapidly phased out of its original role as B-17s began coming off the Boeing assembly lines.
The availability of the surplus airframes and the dire need to provide even a measure of air cover for Atlantic convoys led to 122 examples being reworked as B-18Bs with radar and sometimes MAD booms to detect submarines. The RCAF was supplied with twenty aircraft as Digby Is to carry out this mission as well, and Brazil received two examples. B-18s carried out 11 attacks against U-boats, and sank three.
Phil Butler Air Arsenal North America: Aircraft for the Allies 1938-1945 - Purchases and Lend-Lease p.100 B-18s prior to handover to Brazil
Dana Bell Air Force Colors Vol.1 1926-1942 p.93 photo: B-18 at Clark Field after capture by the Japanese
Ted Williams, Amy E. Williams The American Bomber Plane p.52-55: large artwork depicting an 88th Observation Squadron B-18; photos of B-18As on the production line, and a Bolo being covered in war games camo
David Donald "American Airplanes of World War II" p.98 color profile of a B-18B fitted with a MAD boom
Photo: B-18 fuselages under construction Flying January 1939 p.14
Photo: eight B-18s overflying New York City Aviation September 1939 p.51
Photo: a group of seven 9th BG B-18As in the air Flying & Popular Aviation December 1940 p.48
Ad for the Pioneer Instrument division of Bendix, featuring an image of six B-18s in flight Aviation February 1941 p.21
B-18 3-view drawing Flying April 1944 p.70
Photo: In-flight view of a B-18 refitted as a spray aircraft Aviation Week July 24, 1950 p.39
Robert L. Trimble "Bolo: America's Forgotten Warrior" Air Classics May 1980 extensively illustrated
Photo: B-18s outside of the Santa Monica plant Aeroplane Monthly May 1988 p.264
Photos (color): B-18A N62477 with reworked nose, and B-18A N56847 Warbirds International Oct/Nov 2013 p.61
Jim Winchester American Military Aircraft: A History of Innovation p.125: color profile of a B-18A of the 18th Bombardment Squadron