Later that month the Bulgarian Aviation Corps was expanded to three Aeroplane Platoons. Foreign volunteers began flying operational sorties alongside Bulgarian pilots and carried out reconnaissance, leaflet-dropping and bombing missions. During the war at least three aircraft were shot down. Considerable help was received from the Russians in terms of aircraft, maintenance and training. Due to low aircraft serviceability and frequent accidents, the number of missions flown was relatively low. Despite that, the Bulgarian airmen and their foreign allies were able to gather enough intelligence for the Army General Staff to help successfully capture of the city after a long siege. Although inflicting little physical damage, the bombs had a devastating effect on the defending Turkish garrison's morale and played a crucial part in the fall of the city, which was until then considered nearly impregnable.