Complex sentence: Ferdinand withdrew his army, leaving only 700 men with no cannons and a few guns to defend Güns (Koszeg) although Ibrahim Pasha, the Grand Vizier of the Ottomans, did not realize how poorly defended Koszeg was.
Split into simpler sentences: Ferdinand withdrew his army, leaving only 700 men with no cannons and a few guns to defend Güns (Koszeg). The Grand Vizier of the Ottomans, Ibrahim Pasha, did not realize how poorly defended Koszeg was.