The Treaty of Lyck was a treaty between Vytautas the Great, future Grand Duke of Lithuania, and the Teutonic Knights, represented by Marquard von Salzbach, komtur Arnold von Bürglen, and Thomas, son of Lithuanian duke Survila.
[2] Vytautas, in exchange for a military alliance against his cousin Jogaila during the Lithuanian Civil War (1389–1392), agreed to cede Samogitia up to the Nevėžis River and become the Order's vassal.
[4] The Order demanded as hostages his two brothers Sigismund and Tautvilas, wife Anna, daughter Sophia, sister Rymgajla, brother-in-law Ivan Olshanski, and a number of other nobles.
The Knights managed to convince Skirgaila that they were ready to negotiate peace with him, and he even returned from Polotsk to Vilnius anticipating the Teutonic envoy.
[1] The Knights helped Vytautas to wage a war against Jogaila, but the cousins reconciled in 1392 and signed the Ostrów Agreement.