Edzard's energetic approach against his opponents, the East Frisian leaders Hero Oomkens of Esens, Stedesdorf and Wittmund and Edo Wiemken of Jever, whom he quickly managed to subdue, characterized his rule.

Duke George of Saxony was appointed stadtholder of all Frisian territories in 1514 by Maximilian I, Holy Roman Emperor.

Count Edzard saw this as a chance to expand his influence in the province of Groningen, and proclaimed himself protector of the city.

As a result, 24 German dukes and counts invaded the Frisian lands with their troops and devastated the region.

Only when Charles V came to power in the Netherlands did Edzard manage to end the war by getting himself confirmed as ruler of East Frisia.