Schütte-Lanz airship SL 2 set off to bomb Paris: SL 2 was damaged by artillery fire while crossing the front and turned back but the two Zeppelins reached Paris and dropped of bombs, killing only one and wounding eight. On the return journey Z X was damaged by anti-aircraft fire and was damaged beyond repair in the resulting forced landing. Three weeks later LZ 35 suffered a similar fate after bombing Poperinghe. Paris mounted a more effective defense against zeppelin raids than London. Zeppelins attacking Paris had to first fly over the system of forts between the front and the city, from which they were subjected to anti-aircraft fire with reduced risk of collateral damage. The French also maintained a continuous patrol of two fighters over Paris at an altitude from which they could promptly attack arriving zeppelins avoiding the delay required to reach the zeppelin altitude. Two further missions were flown against Paris in January 1916: on 29 January LZ 79 killed 23 and injured another 30 but was so severely damaged by anti-aircraft fire that it crashed during the return journey. A second mission by LZ 77 the following night bombed the suburbs of Asnières and Versailles, with little effect. Airship operations in the Balkans started in the autumn of 1915, and an airship base was constructed at Szentandras. In November 1915 LZ 81 was used to fly diplomats to Sofia for negotiations with the Bulgarian government. This base was also used by LZ 85 to conduct two raids on Salonika in early 1916: a third raid on 4 May ended with it being brought down by anti-aircraft fire. The crew survived but were taken prisoner. When Romania entered the war in August 1916 LZ 101 was transferred to Yambol and bombed Bucharest on 28 August, 4 September and 25 September. LZ 86, transferred to Szentandras and made a single attack on the Ploiești oil fields on 4 September but was wrecked on attempting to land after the mission. Its replacement, LZ 86, was damaged by anti-aircraft fire during its second attack on Bucharest on 26 September and was damaged beyond repair in the resulting forced landing, and was replaced by LZ 97. At the instigation of the Kaiser a plan was made to bomb Saint Petersburg in December 1916. Two Navy zeppelins were transferred to Wainoden on the Courland Peninsula. A preliminary attempt to bomb Reval on