Gedvydas together with his brother Tautvilas and uncle Vykintas waged a civil war against Mindaugas.
On the Protva River they defeated and killed the first Prince of Moscow Mikhail Khorobrit, but near Zubtsov lost to the Duke of Vladimir-Suzdal.
They formed a powerful coalition with the Samogitians, the Livonian Order, and Vasilko of Volhynia in opposition to Mindaugas.
Tautvilas' and Gedvydas' forces retreated to defend themselves in Vykintas' castle in the present-day Rietavas municipality.
This is the last mention of Gedvydas in written sources, and historians assume he perished in the battle.