In the winter of 343 BC, Artaxerxes set off for Egypt. The Egyptian army, headed by Nectanebo, consisted of 60,000 Egyptians, 20,000 Libu, and as many Greek mercenaries.[24] In addition, Nectanebo had a number of flat-bottomed boats intended to prevent an enemy from entering the Nile mouths.[25] The vulnerable points along his Mediterranean sea border and east boundary were protected by strongholds, fortifications and entrenched camps.[25] Persian forces were strengthened by Mentor and his men, well acquainted with the eastern border of Egypt, and by 6000 Ionians.[3]