unit, and according to Jerzy Cynk and other Polish historians, the actual number of victories for No. 303 Squadron was about 55–60. According to Polish historian Jacek Kutzner, the verified number of kills of 303 Squadron is around 58.8, which would still place it above all other squadrons for verified kills. This is presented by Kutzner's chart, which shows Polish confirmed kills (left column), confirmed kills of all Allied squadrons, including Polish (central column) and real German losses on each day when No. 303 Squadron was involved in air combat (right column). In its first seven days of combat, the squadron claimed nearly 40 enemy aircraft. War over Europe 1941 By 1941, the immediate threat to the UK was over and RAF Fighter Command formulated more offensive fighter operations over occupied Europe. One of these was codenamed "Rhubarb", improvised low-level strafing attacks against opportunist targets on the ground. No. 303 flew its first "Rhubarb"' sorties on 22 January 1941. Six Hurricanes led by F/L Henneberg attacked 1./JG 26's airfield at Crecy, killing one ground crewman and destroying two Bf 109s, also wounding a pilot. In late January 1941, the squadron converted to the Supermarine Spitfire Mk I. In February, the unit participated in the first fighter offensive sweeps, usually escorting a small number of light bombers. In early April 1941, No. 306 (Polish) Squadron arrived at Northolt, and with No. 303 formed No. 1 Polish Fighter Wing. No. 601 Squadron RAF, also stationed at Northolt, complemented the two Polish units. The Wing was commanded by W/C Johnny Kent with W/C Urbanowicz. On 12 April 1941, six No. 303 Spitfires led by S/L Henneberg carried out a series of strafing attacks on German airfields. S/L Henneberg's Spitfire IIa (P8029) was hit by flak and the pilot had to ditch in the channel; despite an intensive search and rescue operation, he was never found. On 11 April 1941, F/L Kustrzyński shot down a Bf109 during a rhubarb over France. On 16 April 1941, the Polish Wing flew its first "Circus" escort operation. Engaged by Bf 109s, two Poles were lost: P/O Waszkiewicz and P/O Mierzwa. On 18 June 1941, No. 303 pilots claimed four Bf 109s without loss; two to P/O Drobiński, as RAF Fighter Command claimed 10 destroyed (The Jagdwaffe suffered no losses). On 21 June, Drobiński badly damaged the Bf 109F-2 of Oberst Adolf Galland, CO of JG 26, who