The first air strike against Bulgarian targets was carried out by 4 Yugoslav Dornier Do 17Kb-1 on 6 April 1941 on the city of Kyustendil and its railway station killing 47 and injuring 95, mostly civilians. The air strikes intensified in the following days; British Royal Air Force units based in Greece participated in the attacks as well. At the end of April, the 2nd and 5th Bulgarian armies occupied Greek and Yugoslav territories according to an agreement with the Third Reich. As a part of the joint armed forces' effort on 26 June 1941 6 Avia B.71 and 9 Dornier Do 17M bombers were transferred to the Badem Chiflik airfield near Kavala (in Greece). They were tasked with anti-submarine patrols and air support for Italian shipping over the adjacent area of the Aegean Sea. In addition 9 Letov Š.328s based in Badem Chiflik provided the ground troops with air reconnaissance. At the Black Sea shores the "Galata" Fighter Orlyak was established at NAS Chaika, Varna, with the 10 Bf 109E-4s and 6 Avia B.534s. The S.328s were also used for anti-submarine patrols over the Black Sea, flying out of the Sarafovo and Balchik airfields. At the end of 1941 the inventory of His Majesty's Air Troops consisted of 609 aircraft of 40 different types.