Alexander participated in two battles against the Teutonic Knights: in 1410 at Grunwald and in 1422 at Marienburg. In 1420, he also defended Moldavia against the first incursion by Ottomans at Cetatea Albă. He also got involved in the power struggles of Wallachia, by helping Radu II Prasnaglava in 1418–1419 and Alexandru I Aldea in 1429, mostly in order to prevent the capture of Chilia.