On 7 August 1944, at 21:40, the two-man crew of a de Havilland Mosquito XII with registration HK230 of 307 Squadron took off from Church Fenton base for an intruder mission around Soesterberg and Deelen. A second aircraft carried out a similar mission to Eindhoven and Gilze-Rijen. Royal Air Force bombers bombed targets in Northern France that night and the two intruders had to provide indirect protection.

German airfields were defended by anti-aircraft guns (‘flak’) and the low and slow-flying intruders were vulnerable if discovered. A German flak managed to shoot down the HK230. The twin-engined Mosquito crashed into the moat of Fort Westervoort at a quarter to 12, killing both crew members.

The pilot was Squadron Leader Ryszard Zwoliński, born on 11 September 1909. He had been with the Squadron since its formation and was held in high regard. His navigator was Warrant Officer Henryk Gajewski, born on 16 December 1918. Both were involved in some of the Squadron's successes. As a crew, they jointly claimed a Junkers 88 as damaged on 15 February 1943. Their bodies were recovered from the wreckage and buried. They now rest side by side in the Moscowa cemetery in Arnhem in graves 30 and 31.

Poles in the Royal Air Force and intruder missions
Many Poles who escaped the German occupation of their country in 1939 served in specific Polish Squadrons in the British Royal Air Force. One of these was 307 Squadron, which had been formed in September 1940 and specialised in night fighters. In the early years, the Squadron flew missions to intercept German bombers during night bombing raids over England. When these became less frequent in 1943 and the battle moved to the continent, the Squadron flew so-called intruder missions. German night fighters inflicted heavy losses on the Allied bombers during their nightly attacks on German industry and used airfields in Germany and the occupied territories for this purpose. They were particularly vulnerable there during take-off and landing. For this reason, the Royal Air Force sent individual aircraft to these bases, hoping to surprise German night fighters there.