The interregnum concluded on 12 December 1575 when primate Jakub Uchański declared Maximilian II, Holy Roman Emperor, as the next king. The decision was condemned by the anti-Habsburg coalition, which demanded a "native" candidate. As a compromise, on 13 December 1575 Anna Jagiellon – sister of Sigismund Augustus and a member of the Jagiellonian dynasty – became the new monarch. The nobles simultaneously elected Stephen Báthory as co-regent, who ruled "jure uxoris". Báthory's election proved controversial – Lithuania and Ducal Prussia initially refused to recognize the Transylvanian as their ruler. The wealthy port city of Gdańsk (Danzig) staged a revolt, and, with the help of Denmark, blockaded maritime trade to neutral Elbląg (Elbing). Báthory, unable to penetrate the city's extensive fortifications, succumbed to the demands for greater privileges and freedoms. However, his successful Livonian campaign ended in the annexation of Livonia and the Duchy of Courland and Semigallia (modern-day Latvia and southern Estonia), thus expanding the Commonwealth's influence into the Baltics. Most importantly, Poland gained the Hanseatic city of Riga on the Baltic Sea.