this reason while we regard Hannibal as being a good general in very many ways, we should lay especial stress on the fact that after spending many years in a hostile country and meeting with great variety of fortune he frequently by his cleverness worsted the enemy in partial engagements, whereas he never met with disaster to himself in spite of the numerous and severe battles in which he engaged,
so great was the care he took of his own safety.
And very properly too; for when the commander is safe and sound, even if a total defeat takes place, Fortune furnishes many means for retrieving the loss,
but if he falls, just as in the case of the pilot of a ship, even if Fortune give victory to the soldiers, it is of no service to them, as all their hopes depend upon their leaders.
So much for those who fall into such errors from ostentation and childish vanity or from inexperience or contempt of the enemy.
One or other of these is always the cause of such accidents. . . .
Suddenly letting down the portcullis which they had raised somewhat higher by mechanical means, they attacked the intruders and capturing them crucified them before the wall.
Walbank Commentary