ENThe Grand Duchy of Lithuania established on the eastern coast of the Baltic sea at the end of the 12th and beginning of the 13th centuries became immediately involved in the struggle with its neighbours. For this reason the military aspect of Lithuanian social development up to the very beginning of the 15th century has received special attention. The battles were both offensive in the eastern direction and defensive-in the west. As the present territory of Lithuania was the scene of defensive battles against the Teutonic Order between the 13th-the and early the 15th centuries, its castles played an important role. Despite this, due to different reasons the technique of building of stone was far behind in Lithuania compared with the Western Europe. According to the most recent data the first stone castles appeared in Lithuania during the first half of the 14th century. However, absolutely reliable data goes back only to the second half of the 14th century. In the present territories of Lithuania and Belorus-the former Lithuanian territories eleven stone castles from the 14th to 15th centuries are known Gardinas, Kaunas, Krėva, Liškiava (unfinished), Lyda, Medininkai, Naugardukas, Senieji Trakai, Trakai Pusiasalis castle, Trakai Sala castle and Vilnius. Greater or smaller remains of these sites have been preserved until now. [p. 162].