[1] With the help of his brother Kęstutis (who defended the western border of the Duchy) he created an empire stretching from the present Baltic states to the Black Sea and to within 80 kilometres (50 miles) of Moscow.

The division of their dominions is illustrated by the fact that Algirdas appears almost exclusively in East Slavic sources, while Western chronicles primarily describe Kęstutis.

The Teutonic Order in the northwest and the Golden Horde in the southeast sought Lithuanian territory, while Poland to the west and the Moscow principality to the east were generally hostile competitors.

Although Algirdas engineered the election of his son Andrius as Prince of Pskov and a powerful minority of Novgorod Republic citizens supported him against the Moscow principality, his rule in both commercial centres was (at best) precarious.

[7] An important feat by Algirdas was his victory over the Tatars in the Battle of Blue Waters at the Southern Bug in 1362, which resulted in the breakup of the Kipchaks and compelled the khan to establish his headquarters in the Crimea.

[8] According to modern historians, "For Gediminas and Algirdas, retention of paganism provided a useful diplomatic tool and weapon ... that allowed them to use promises of conversion as a means of preserving their power and independence".

Algirdas balanced himself between Moscow principality and Poland, spoke Lithuanian and Ruthenian (among other languages) and followed the majority of his pagan and Orthodox subjects rather than to alienate them by promoting Roman Catholicism.

[23] Algirdas features in the 2021 video game Age of Empires II: Definitive Edition in the Dawn of the Dukes campaign, detailing the exploits of himself and his brother Kęstutis.