The Egyptian army immediately broke

The Egyptian army immediately broke up its encampments in the
neighborhood of Alexandria, and marched to the eastward to meet these
new invaders, Caesar followed them with all the forces that he could
safely take away from the city. He left the city in the night, and
unobserved, and moved across the country with such celerity that he
joined Mithradates before the forces of Ptolemy had arrived. After
various marches and maneuvers, the armies met, and a great battle was
fought. The Egyptians were defeated. Ptolemy's camp was taken. As the
Roman army burst in upon one side of it, the guards and attendants of
Ptolemy fled upon the other, clambering over the ramparts in the utmost
terror and confusion. The foremost fell headlong into the ditch below,
which was thus soon filled to the brim with the dead and the dying;
while those who came behind pressed on over the bridge thus formed,
trampling remorselessly, as they fled, on the bodies of their comrades,
who lay writhing, struggling, and shrieking beneath their feet. Those
who escaped reached the river. They crowded together into a boat which
lay at the bank and pushed off from the shore. The boat was overloaded,
and it sank as soon as it left the land. The Romans drew the bodies
which floated to the shore upon the bank again, and they found among
them one, which, by the royal cuirass which was upon it, the customary
badge and armor of the Egyptian kings, they knew to be the body of
Ptolemy.

The victory which Caesar obtained in this battle and the death of Ptolemy
ended the war. Nothing now remained but for him to place himself at the
head of the combined forces and march back to Alexandria. The Egyptian
forces which had been left there made no resistance, and he entered the
city in triumph. He took ArsinoŠ» prisoner. He decreed that Cleopatra
should reign as queen, and that she should marry her youngest brother,
the other Ptolemy,--a boy at this time about eleven years of age. A
marriage with one so young was, of course, a mere form. Cleopatra
remained, as before, the companion of Caesar.