Complex sentence: In 1444, he was appointed as a commander of the short-lived League of Lezhë, which proclaimed him "Chief of the League of the Albanian people" and defended the region of Albania against the Ottoman Empire for 25 years.
Split into simpler sentences: In 1444, he was appointed as a commander of the short-lived League of Lezhë, which proclaimed him "Chief of the League of the Albanian people". He was "either" able to defend the region of Albania against the Ottoman Empire for 25 years.