The earliest sizable towns yet discovered by archaeologists were fortified. At least one historian believes that the need for walls as protection from war was the impetus for the first cities, not the agricultural revolution. Most ancient city sites show evidence of both walls and of being destroyed at least once in their existence. Heinrich Schlieman, the first excavator of Troy, had to decide which of several successive destroyed cities he found on the site was the Troy of the Iliad. If the walls discovered at most ancient cities are evidence of war, the subsequent evidence of destruction is evidence that the ancients had also mastered siege warfare_the taking of walled cities by force.

Siege engines.

The first equipment designed specifically to take walled cities for which we have evidence was a ladder with wheels on its base depicted in an Egyptian relief. The engraving shows the ladder already wheeled up against an enemy wall and soldiers climbing up to the fight. Most cities sacked in the third millennium BC and before were probably taken by scaling the walls or breaking down the gates.

Prior to the time of Alexander the Great, the cultures and kingdoms of Mesopotamia were the most advanced in building specialized equipment for taking cities. The principle construction material in this region was sun-dried, or later fire-baked, mud bricks. One important siege engine from this area was a battering ram sheltered within rolling protective framework that could be rolled up against the mud brick walls. Under the cover of the roof, engineers inside could use the metal tipped ram to break and gouge out bricks, eventually crumbling sections of the wall and forming a breach that could be stormed.

As the cities got larger and fortifications stronger, new equipment was required. The structure covering the battering rams increased in size, becoming movable towers. When wheeled up against the walls, archers from the top could fire down or along the walls. A ramp lowered from the tower to the wall, allowed attackers to advance into the city. More attackers could climb up within the covered tower before crossing over into the attack.

Catapults, the first long-range missile weapons, were invented in Syracuse, Sicily, in 399 BC. The king of Sicily, Dionysius I, assembled craftsmen to design machines to aid his assault of an island fortress on the coast. Catapults hurled large stones against walls from a distance, minimizing the danger to attackers while slowly crumbling the defenses. The stones fired against the wall built up at its base, forming a rough assault ramp into the breach. Within sixty years, advanced catapults were standard weapons in the armies of both Greece and Persia.

Famous sieges.

The best-known siege of antiquity was the destruction of Jericho by Joshua's trumpet as recorded in the Bible. Other well-known sieges were the taking of Tyre by Alexander the Great and the siege of Alesia by Julius Caesar in .

Tyre.
In 332 BC Alexander advanced down the Eastern Mediterranean coast after his victory at Issus. The coastal cities surrendered one by one, except Tyre, an island fortress one half mile off the coast with walls 150 feet high. The Greeks began building a 200-foot causeway out to the island. When the Tyrians began firing on the construction crews with catapults, Alexander built two 150-foot towers on the causeway armed with catapults to fire back. These were burned by a fire ship but Alexander responded by widening the causeway and building more towers. Alexander anchored ships off the walls to serve as platforms for battering rams. The walls of the city were finally breached from the ships and causeway. The elite troops of Alexander's army led the assault, infuriated by Tyrian tactics. More than 8000 Tyrians were killed in the final attack and the remaining 30,000 inhabitants were sold into slavery.

Alesia.
In 52 BC Julius Caesar was attempting to subjugate the Celtic tribes of Gaul (modern France) at the head of 12 Roman legions. He bottled up a leader of the Gauls, Vercingetorix, in the hilltop town of Alesia (modern Alise- Sainte-Reine near Dijon). Expecting a relief force to break his siege, Caesar's problem was to defend the long circumference, keeping Vercingetorix in while being able to respond to an attack from the outside. Caesar surrounded Alesia with a 14-mile-long double fortification of wooden walls, walkways, towers every 800 feet, deep trenches and pits filled with spikes.