At the same time, an anti-Vytautas rebellion broke out in Samogitia. The Teutonic Knights wanted to use that against Lithuania and invited Švitrigaila to overthrow Vytautas. Instead, Švitrigaila reconciled with Jogaila during a meeting between King Sigismund and Jogaila in Košice in May 1419. Švitrigaila received Opoczno and restored annual income from the Wieliczka Salt Mine. However, that did not reconcile him with Vytautas. After the failed mediation by King Sigismund between Lithuania and the Teutonic Knights, both Poland and Lithuania began preparing for the Gollub War. Polish nobles understood the importance of neutralizing Švitrigaila, who continued to receive Teutonic offers for an alliance, and sent a delegation to persuade Vytautas to forgive his cousin. Eventually, Vytautas relented and the official agreement was concluded in August 1420. Švitrigaila swore loyalty and received Principalities of Briansk, Chernigov, Trubetsk, and Novgorod-Seversk.