The lands that today comprise Croatia were part of the Austro-Hungarian Empire until the close of World War I. In 1918, the Croats, Serbs, and Slovenes formed a kingdom known after 1929 as Yugoslavia. Following World War II, Yugoslavia became a federal independent Communist state under the strong hand of Marshal TITO. Although Croatia declared its independence from Yugoslavia in 1991, it took four years of sporadic, but often bitter, fighting before occupying Serb armies were mostly cleared from Croatian lands. Under UN supervision, the last Serb-held enclave in eastern Slavonia was returned to Croatia in 1998. In April 2009, Croatia joined NATO; it is a candidate for eventual EU accession.
Croatia is located in southeastern Europe, bordering the Adriatic Sea, between Bosnia and Herzegovina and Slovenia.
Sisak is a city in central Croatia. The city's population in 2011 was 33,049, with a total of 49,699 in the administrative region and it is also the administrative center of the Sisak-Moslavina county. Sisak is located at the confluence of the Kupa, Sava, and Odra rivers, 57 km (35 mi) southeast of the Croatian capital Zagreb.
Sisak is usually considered to be where the Posavina begins, with an elevation of 99 m.
Sisak is Croatia's biggest river port and a center of the river shipping industry. Sisak lies on the main road Zagreb-Sisak-Petrinja (M12.2) and the railroad Zagreb-Sisak-Sunja.