The Mongol war machine moved south and in 1237 attacked the Song city of Anfeng (modern Shouxian, Anhui Province) "using gunpowder bombs pao to burn the towers." These bombs were apparently quite large. "Several hundred men hurled one bomb, and if it hit the tower it would immediately smash it to pieces." The Song defenders under commander Du Gao (杜杲) rebuilt the towers and retaliated with their own bombs, which they called the "Elipao," after a famous local pear, probably in reference to the shape of the weapon. Perhaps as another point of military interest, the account of this battle also mentions that the Anfeng defenders were equipped with a type of small arrow to shoot through eye slits of Mongol armor, as normal arrows were too thick to penetrate.