History of Lithuania
On February 16, 1918, Lithuania was re-established as a democratic state. It remained independent until the outset of World War II, when it was occupied by the Soviet Union under the terms of the Molotov–Ribbentrop Pact. Following a brief occupation by Nazi Germany after the Nazis waged war on the Soviet Union, Lithuania was again absorbed into the Soviet Union for nearly 50 years. In 1990–1991, Lithuania restored its sovereignty with the Act of the Re-Establishment of the State of Lithuania. Lithuania joined the NATO alliance in 2004 and the European Union as part of its enlargement in 2004.
Flag of Lithuania
The earliest known flags with a Lithuanian identity were recorded in the 15th-century "Banderia Prutenorum", written by Jan Długosz. At the Battle of Grunwald in 1410, two distinct flags were present. The majority of the 40 regiments carried a red banner depicting a mounted knight in pursuit. This flag, known as the "Vytis", would eventually be used as the Lithuanian war flag, and again in 2004 as the state flag. 
The remainder of the regiments carried a red banner displaying the Columns of Gediminas. Those that bore the Vytis, also known as the Pahonia, were armies from the Grand Duchy of Lithuania, while those who bore the Columns of Gediminas were from noble families of Lithuania. Until the end of the 18th century, when it was annexed by the Russian Empire, the Grand Duchy of Lithuania used the Vytis as its flag.