Mindaugas (ca.

1203 – fall 1263) is the first known Grand Duke of Lithuania and the only King of Lithuania.

Little is known of his origins, early life, or rise to power; he is mentioned in a 1219 treaty as an elder duke, and in 1236 as the leader of all the Lithuanians.

The contemporary and modern sources discussing his ascent mention strategic marriages along with banishment or murder of his rivals.

He extends his domain into regions southeast of Lithuania proper during the 1230s and 1240s.

In 1250 or 1251, during the course of internal power struggles, he is baptized as a Roman Catholic; this action enables him to establish an alliance with the Livonian Order, a long-standing antagonist of the Lithuanians.

During the summer of 1253, he is crowned King of Lithuania, ruling between 300,000 and 400,000 subjects.

While his ten-year reign is marked by various state-building accomplishments, Mindaugas's conflicts with relatives and other dukes continue, and Samogitia (western Lithuania) strongly resists the alliance's rule.

His gains in the southeast are challenged by the Tatars.

He breaks peace with the Livonian Order in 1261, possibly renouncing Christianity, and is assassinated in 1263 by his nephew Treniota and another rival, Duke Daumantas.

His three immediate successors are assassinated as well.

The disorder is not resolved until Traidenis gains the title of Grand Duke ca.

1270.

Although his reputation was unsettled during the following centuries and his descendants were not notable, he gained standing during the 19th and 20th centuries.

Mindaugas was the only King of Lithuania; while most of the Lithuanian Grand Dukes from Jogaila onward also reigned as Kings of Poland, the titles remained separate.

Now generally considered the founder of the Lithuanian state, he is also now credited with stopping the advance of the Tatars towards the Baltic Sea, establishing international recognition of Lithuania, and turning it towards Western civilization.

In the 1990s the historian Edvardas Gudavičius published research supporting an exact coronation date – 6 July 1253.

This day is now an official national holiday, Statehood Day.