During the whole march they were harassed by the Arabs, and many were cut off and killed. Marches were always performed at night, and at ten o'clock in the morning they halted for the day, preparing themselves for slumber by a dip in the Nile. On the 21st of July they advanced from Omdinar, and at ten o'clock made out the enemy drawn up in line of battle. They had constructed a large entrenched camp, with forty pieces of ancient cannon incapable of movement. In this camp were 20,000 infantry, Janizaries, Spahis, and militia from Cairo. On the right were the Mameluke cavalry, some 10,000 strong, with one or two foot-soldiers to each horseman. To the left of the Mamelukes, and between them and the Pyramids, were some 3000 Arab horse.
The French army was drawn up in the same order as in their last fight, in great squares of divisions, the left resting on the Nile, and the right on a large village. Napoleon, with his staff, reconnoitered the enemy's entrenched camp, and by means of telescopes discovered that the cannon were not upon field-carriages, but were simply heavy ship guns that had been taken from their flotilla, and were served by the sailors. They, therefore, could not be moved, and it was evident that if the infantry left the camp they must do so without guns. The entrenchment itself was not formidable; it had been begun but three days before, and although it might be impracticable for cavalry, it would offer no serious obstacle to an attack by infantry.
The discovery that the cannon were immovable, decided Napoleon in his dispositions for the battle, and he gave orders that his army should move across to his right, and should thus be concentrated for the attack upon the Mamelukes and Arabs. Mourad Bey, seeing Napoleon's object, at once ordered two-thirds of his cavalry to charge the French while they were in motion, while the others were to remain near the entrenched camp. So rapidly did they sweep down, that the French squares fell into some confusion, and Desaix, with his division, which formed the head of the column, had difficulty in maintaining themselves, their ranks being somewhat broken by a grove of palm-trees through which they were passing. They, however, received the Mamelukes with so terrible a fire of musketry and grape-shot that the charge was not pressed home. The Mamelukes, however, fought with desperate courage, sweeping round the French squares, and even endeavouring to back their horses into the line of bayonets, in hopes of breaking the wall of steel.