Sextus Iulius Frontinus, vir consularis de re militari

Quintus Sertorius in Spain, when he had to cross a river with the enemy pressing from the rear, built a rampart on its bank in the shape of a crescent moon and set it on fire, loaded with materials. Thus, having excluded the enemies, he crossed the river freely. Similarly, Pelopidas the Theban sought a crossing in the Thessalian war. For, having encompassed a place on the bank larger than the camp, he constructed a rampart of logs and other material and set it on fire. While the enemies were kept away by the flames, he himself crossed the river. Quintus Luctatius Catulus, when pushed back by the Cimbri and having only one hope of safety if he could cross the river—whose bank the enemies were holding—showed his forces on a nearby mountain as if he were about to pitch camp. He instructed his men not to unpack their baggage or set down their burdens, and that no one should depart from their ranks or standards. And, the more to confirm the enemy's persuasion, he ordered a few tents to be erected in sight, fires to be made, and some to build the rampart, while others went out for wood so they would be seen. The Cimbri, believing this was genuinely happening, also chose a place for their camp and dispersed into the nearby fields to gather the necessities for those intending to stay. This gave Catulus the opportunity not only to cross the river but also to attack their camp. Croesus, when he could not cross the Halys by a ford and had no means of making ships or a bridge, dug a trench on the upper side behind his camp and brought the river's water to the rear of his army. Gnaeus Pompeius at Brundisium, when he had proposed to depart from Italy and transfer the war, and Caesar was pressing from the rear, obstructed certain roads as he was about to board the fleet. He blocked others with walls, cut others with trenches, and covered these with sharpened stakes and hurdles piled with earth. He protected certain approaches that led to the port with beams crossed and built in a dense order, forming a huge mass. With these things completed, he left a few archers before the walls to simulate the holding of the city, and led his other forces to the ships without any tumult. When he was sailing away, the archers soon followed in small boats, although they had departed via known paths. Gn. Duillius the consul, in the port of Syracuse, which he had entered rashly, was closed in by a chain thrown across the entrance. He moved all his soldiers to the stern, and with the great strength of the rowers, made the ships rise. The prows were lifted and passed over the chain. Once that part was overcome, the soldiers moved to the prows, and the weight turned toward them caused the ships to descend over the chain. Lysander the Lacedaemonian, when he was being besieged in the port of the Athenians with his entire fleet, cut off by the enemy's ships from the side that...