Siege engines and the art of siegecraft are very interesting, especially as they actually declined for a time. Alexander’s surviving lieutenants, the Diadochi who squabbled and squandered his empire, maintained a high level of excellence but it declined thereafter.
The siege can be brought to victory, and the subject city to submission, by the means of storm, surrender, starvation, or shenanigans of a treacherous nature.
The big problem with starving a city until it gives up is that feeding an army that’s unable to move and will soon exhaust nearby food supplies is bloody difficult. It gives time for the city’s allies to gather and attack the besiegers, and, often far worse, time for things like chronic diarrhoea, dysentery and despondency to grow amongst the attacking force.
Shenanigans of a treacherous nature can be the easiest way to resolve a siege. The traitor gets some money (or murdered for being a perfidious git), the army gets victory and the city gets sacked because it didn’t surrender.
Surrender can work well… or not. Alexander and Hannibal were pretty merciful and generous to surrendering cities. Tamerlane was not. Nevertheless, refusing to surrender and then getting beaten is usually far worse.
To try and give the attacking side a better shot of swift victory an array of ingenious siege engines were developed. From Alexander the Great to the Black Prince there was not that much improvement. One particularly exciting device was the Theban flame-thrower. Basically, they took a big tree trunk, cut it along the length, hollowed out the middle to make it a tube and then stuck it back together. Then, they put massive bellows at one end and a flaming cauldron at the other. It was used in the Battle of Delium, according to Thucydides:
“The Boeotians constructed a strange device, which according to the description in Thucydides (4.100) seems to be a kind of flamethrower, and used this weapon to set fire to Delium and chase away the Athenians. Only about 200 Athenians were killed; the rest were allowed to escape.”
More well-known, and obvious, was the ram, which often had a cunning roof to stop defenders throwing rocks and so forth upon the chaps trying to smash their walls.
The ancients also used enormous siege towers of many levels, within which soldiers could hide. A high level drawbridge could be lowered rapidly, enabling the soldiers hiding within to run onto the defending walls and try to open its gates to the aggressors.
Archimedes was a genius of Syracuse, and for a few years in the Second Punic War successfully prevented the talented Roman consul Marcellus from taking the city, virtually single-handed. He created a number of brilliant defensive weapons, and although what they actually were is in dispute, it is a matter of consensus that he successfully kept the Romans from taking the city for two years by his genius. Amongst the claims are a claw which could be dropped from a crane onto a ship and then raised, sinking the ship, and a heat ray so powerful it made ships burst into flames.
In medieval times, siege towers (known as belfries) were still in use, as was the ram (although the wheeled shelter was now called a sow and sometimes protected men with picks).
However, they also used the magnificent trebuchet: a cunningly designed catapult of substantial size which could hurl rocks of 200lb or 300lb several hundred yards. A smaller version, the couillard, was also available for use. Trebuchets could be used in a rather less hygienic but more cunning way, as a means of delivering festering, disease-ridden carcasses into the city, encouraging plague and woe therein.
Alongside the trebuchet, the mangonel is probably the best-known medieval siege weapon. It’s basically a big catapult that hurled a single large rock at a time. Unlike the trebuchet, which sent its ammunition high into the air, the mangonel’s flew on a lower trajectory and was used for smashing walls rather than crushing buildings and people within the city.
After thousands of years of enormous wooden siege engines with the occasional bit of metal here and there the likes of the trebuchet were outclassed by guns. One of the most important things the cannon achieved was the ultimate and lasting defeat of Byzantium. The Second Rome had repelled countless invasions thanks to its naturally excellent defensive position and its staggeringly effective walls. But no walls could withstand the cannon of the Ottoman Turks, and the city fell in the mid-15th century. It is now known as Istanbul.