During the Byzantine civil wars Ivan Alexander regained control over several towns in Thrace and the Rhodopes but his frequent interference in the internal affairs of Byzantium hampered any closer relations between the two counties despite the peace established in 1332. In 1352 Turkish forces invaded Bulgaria anew, raiding Thrace, particularly the vicinities of Aitos, Yambol, and Plovdiv, and capturing rich spoils. In the same year the Ottomans seized their first fortress on the Balkans, Tsimpe on the Gallipoli peninsula, setting firm foot in Europe. Until 1354 Ottoman forces again ravaged the lands around Yambol and Plovdiv as well as the lower valleys of the Maritsa and Tundzha rivers.