Louis assembled his armies in Temesvár (now Timișoara in Romania) in February 1365. According to a royal charter that year, he was planning to invade Wallachia because the new voivode, Vladislav Vlaicu, had refused to obey him. However, he ended up heading a campaign against the Bulgarian Tsardom of Vidin and its ruler Ivan Sratsimir, which suggests that Vladislav Vlaicu had in the meantime yielded to him. Louis seized Vidin and imprisoned Ivan Stratsimir in May or June. Within three months, his troops occupied Ivan Stratsimir's realm, which was organized into a separate border province, or banate, under the command of Hungarian lords.