Handley Page O/400
One of the first purpose built heavy bombers. The design order was issued by the Admiralty for the RNAS at the end of 1914, but the O/400 did not enter active service until March 1917, when it was used against German U-boat bases. It was then used against Germany shipping and ports, and had an increasing impact as the number of aircraft in operation increased. In addition to service on the western front, one O/400 was sent to the Aegean, where it operated against the Turks for three months before engine failure forced it out of action, and another was sent to Palestine to help General Allenby, again against the Turks, where its size made as much impact as its bombs. When the RNAS and RFC merged to form the RAF, the O/400 became its standard heavy bomber, but despite efforts to turn the O/400 into a transport plane, they had all gone out of service by the summer of 1923.
How to cite this article: Rickard, J. (13 November 2000), Handley Page O/400, http://www.historyofwar.org/articles/weapons_hp0400.html