V-2 rocket offensive began on 8 September 1944, when "Lehr- und Versuchsbatterie No. 444" () launched a single rocket guided by a radio beam directed at Paris. Wreckage of combat V-2s occasionally contained the transponder for velocity and fuel cutoff. The painting of the operational V-2s was mostly a ragged-edged pattern with several variations, but at the end of the war a plain olive green rocket also appeared. During tests, the rocket was painted in a characteristic black-and-white chessboard pattern, which aided in determining if the rocket was spinning around its longitudinal axis. The original German designation of the rocket was "V2",
Operation Crossbow Watson-Watt) was formed in September 1943 regarding the suspected V-2 rocket, and after the 1944 crash of a test V-2 in Sweden, "transmitters to jam the guidance system of the rocket" were prepared. A British sound-ranging system provided "trajectory [data] from which the general launching area could be determined", and the microphone(s) in East Kent reported the times of the first V-2 strikes on September 8, 1944: 18:40:52 and 18:41:08. On March 21, 1945, the plan for the "Engagement of Long Range Rockets with AA Gunfire" which called for anti-aircraft units to fire into a radar-predicted airspace to intercept the