[2] After the German–Soviet invasion of Poland of 1939, most of the flying personnel and technicians of the Polish Air Force were evacuated to Romania and Hungary, after which thousands found their way to France.A small improvised Polish unit at Salon and Clermont-Aulnat (now Clermont-Ferrand Auvergne Airport) operated the equally inadequate Koolhoven F.K.58 from 30 May commanded by Captain Walerian Jasionowski.The British government informed General Sikorski that, at the end of the war, Poland would be charged for all costs involved in maintaining Polish forces in Britain.[citation needed] Dowding had been doubtful about integration of Polish pilots within British squadrons due to language issues and wanted all-Polish units.The fighter squadrons, flying the Hawker Hurricane, first saw action in the third phase of the Battle of Britain in late August 1940, quickly becoming highly effective.Polish flying skills were well-developed from the invasion of Poland and being highly motivated by patriotism for revenge the pilots were regarded as fearless and sometimes bordering on reckless.Although at first the Poles memorised basic English sentences to identify themselves if shot down over Britain to avoid being mistaken as Germans, Ingersoll wrote that such pilots returned with "a girl on each arm.This resulted in the creation of a dedicated Polish Air Force staff college at RAF Weston-super-Mare, which remained open until April 1946.A large memorial to Polish Air Force squadrons in the war is situated on the floor of the north aisle of the reconstructed Wren church, St Clement Danes, London.[citation needed] The Polish-American fighter ace Francis S. "Gabby" Gabreski flew his first combat missions attached to a Polish RAF squadron.