an observer were used to scout enemy positions and bomb their supply bases. Because they were large and slow, these aircraft made easy targets for enemy fighter aircraft. As a result, both sides used fighter aircraft to both attack the enemy's two-seat aircraft and protect their own while carrying out their missions. While the two-seat bombers and reconnaissance aircraft were slow and vulnerable, they were not defenseless. Two-seaters had the advantage of both forward- and rearward-firing guns. Typically, the pilot controlled fixed guns behind the propeller, similar to guns in a fighter aircraft, while the observer controlled one with which he could cover the arc behind the aircraft. A tactic used by enemy fighter aircraft to avoid fire from the rear gunner was to attack from slightly below the rear of two-seaters, as the tail gunner was unable to fire below the aircraft. However, two-seaters could counter this tactic by going into a dive at high speeds. Pursuing a diving two-seater was hazardous for a fighter pilot, as it would place the fighter directly in the rear gunner's line of fire; several high scoring aces of the war were shot down by "lowly" two-seaters, including Raoul Lufbery, Erwin Böhme, and Robert Little. Even Manfred von Richthofen, the highest scoring ace of WWI, was once wounded and forced to crash land from the bullets of a two-seater, though he did survive the encounter and continued flying after he recovered. Strategic bombing The first aerial bombardment of civilians occurred during World War I. In the opening weeks of the war, zeppelins bombed Liège, Antwerp, and Warsaw, and other cities, including Paris and Bucharest, were targeted, In January 1915 the Germans began a bombing campaign against England that was to last until 1918, initially using airships. There were 19 raids in 1915, in which 37 tons of bombs were dropped, killing 181 people and injuring 455. Raids continued in 1916. London was accidentally bombed in May, and in July, the Kaiser allowed directed raids against urban centres. There were 23 airship raids in 1916 in which 125 tons of ordnance were dropped, killing 293 people and injuring 691. Gradually British air defenses improved. In 1917 and 1918 there were only eleven Zeppelin raids against England, and the final raid occurred on 5 August 1918, resulting in the death of Peter Strasser, commander of the German Naval Airship Department. By the end of the