:: Crusade of Varna included the "string of events in 1443–44 between the Kingdom of Hungary, the Serbian Despotate, and the Ottoman Empire. It culminated in a devastating Hungarian loss at the Battle of Varna on November 10, 1444." 
 :: Skanderbeg left Ottoman Empire's army after defeat in the Battle of Niš and did not participated in the Crusade of Varna which lasted till November 1444. Therefore I propose to delete "the Crusade of Varna" from the above sentence.