Crossbow was the code name in World War II for Anglo-American operations against the German long range reprisal weapons (V-weapons) programme. The primary V-weapons were the V-1 flying bomb and V-2 rocket, which were launched against Britain from 1944 to 1945 and used against continental European targets as well.

Initial intelligence investigations in 1943 into the progress of German long range weapons were carried out under the code name Bodyline. On 15 November, a larger operation was set up under the name Crossbow. Post-war, Crossbow operations became known as "Operation Crossbow" particularly following the 1965 film of the same name.

Crossbow included strategic operations against research and development of the weapons, their manufacture, transportation and attacks on their launch site, and fighter intercepts against missiles in flight. At one point, the British government, in near panic, demanded that upwards of 40% of bomber sorties be targeted against the launch sites.^{[citation needed]}

The Crossbow attacks were not very successful, and every raid carried out against a V-1 or V-2 launch site was one fewer raid against other targets in the Third Reich. The diversion of Allied resources from other targets represented a major success for Hitler.

In May 1943 Allied surveillance observed the construction of the first of eleven large sites in northern France for secret German weapons, including six for the V-2 rocket. In November it discovered the first of 96 "ski sites" for the V-1 flying bomb.

Officials debated the extent of the German weapons' danger; some viewed the sites as decoys to divert Allied bombers, while others feared chemical or biological warheads. The Allies received detailed information about V-1, V-2 and Peenemünde research site from the Austrian resistance group around the priest Heinrich Maier. This also included the production sites such as the Raxwerke. When reconnaissance and intelligence information regarding the V-2 became convincing, the War Cabinet Defence Committee (Operations) directed the campaign's first planned raid (the Operation Hydra attack on Peenemünde in August 1943).

The works in France were the German "Site System 1" which was to be 96 fixed launching sites with storage bunkers (the 'ski' shapes) and outdoor ramps. Site System 2 (a reserve) and System 3 were planned. There were also four larger Wasserwerk ("Waterworks") bunker sites: Siracourt, Lottinghen, Nardouet, and Brécourt. Intended for use in January 1944 actual progress in construction, training and supply of V-1s was behind when inspected by German high command in October. French reports and detailed aerial reconnaissance linked with reconnaissance of Peenemünde indicated possibility of 2,000 missiles per day against England. Over half the sites were completed by December but Allied intelligence had identified all 96 by end of January. The first bombing of sites was by USAAF Martin B-26 Marauder medium bombers in early December with RAF Bomber Command starting night-time attacks shortly after but the greater inaccuracy of night bombing against small targets led the Joint Chiefs of Staff to use US heavy bombers in daylight. By the end of December 54 sites had been attacked and seven were destroyed. The bombing continued – by end of March 9 destroyed and 35 seriously damaged, by May 24 destroyed and 58 seriously damaged.

Following Operation Hydra, a few Crossbow attacks were conducted on the "Heavy Crossbow" bunkers of Watten (V-2) and Mimoyecques (actually V-3 rocket cannon) from August and November 1943 respectively. "Crossbow Operations Against Ski Sites" began on 5 December with the "Noball" code name used for the targets (e.g., 'Noball 27' was the Ailly-le-Vieux-Clocher [sic] site, "Noball No. 93" was in the Cherbourg area, "Noball No. 107" was at Grand Parc, and "Noball V1 site No.147" was at Ligescourt).