His reign ended a seven-year unrest period after Mindaugas was assassinated in 1263 and firmly established the Grand Duchy as a pagan state for another hundred years.

[2] Traidenis expanded the Grand Duchy into the territories of Sudovians and Semigalians and strengthened its presence in Black Ruthenia.

Despite Mongol support to Galicia–Volhynia, Traidenis was successful in battle and his control over Black Ruthenia (Novogrudok, Grodno, Slonim, and other cities) was strengthened.

In 1270 he won the Battle of Karuse, fought on ice near Saaremaa, and killed Otto von Lutterberg, master of the Order.

In 1279 the order attacked Lithuanian lands, reaching as far as Kernavė, but on their way back they suffered a great defeat in the Battle of Aizkraukle.