Waiting then for a day on which Ptolemy made an excursion to Canobus he spread a report among his guards that he was going to be set at liberty by the king, and upon this pretence he entertained his own attendants, and sent presents of meat, garlands, and wine to the guards.
When the soldiers, suspecting nothing, had indulged freely in these good things and were quite drunk, he took the friends who were with him and his own servants and about midday they rushed out of the house unnoticed by the guards, and armed with daggers.
As they advanced they met in the square with Ptolemy who had been left in charge of the city, and overawing his attendants by the audacity of their attack, they dragged him from his chariot and shut him up, and now began to call on the people to assert their freedom.
But when no one paid any attention or consented to join the rising, as the whole plan had taken everyone completely by surprise, they retraced their steps and made for the citadel with the intention of forcing the gates and getting the prisoners to join them.
But when this design also failed, as the guards of the prison got word of their intention and made the gates fast, they died by their own hands like brave men and Spartans.
Thus perished Cleomenes, a man tactful in his bearing and address, with a great capacity for the conduct of affairs and in a word designed by nature to be a captain and a prince.
Walbank Commentary