A knight was expensive rather than noble
Becoming a KNIGHT was mostly a question of money. A warhorse, a second horse, a suit of ARMOUR, weapons, and a SQUIRE and servants to maintain it all cost roughly what a small estate produced in a year. The military role existed because the king granted land in exchange for showing up armed and mounted when called.
Full plate ARMOUR, the suit everyone pictures, weighed about 20 to 25 kilograms spread across the whole body — less than a modern soldier's kit and distributed far better. A fit man in a well-fitted harness could run, mount a horse unaided and get up off the ground. The idea that a fallen knight lay there like an upturned beetle, or had to be craned onto his horse, comes from Victorian misreadings and a 1944 Laurence Olivier film.
Sieges were won by waiting and digging
Storming a CASTLE was a last resort because it killed attackers in large numbers. The usual method was a SIEGE: surround it, cut the supply, and wait for the food or the water to run out. Most castles fell to starvation, disease or negotiated surrender rather than assault.
When force was used, the most effective tool was a shovel. Sappers dug a tunnel under a corner TOWER, propped the roof with timber, packed it with pig fat and brushwood and set it alight; the props burned through and the tower came down with the tunnel. That is how King John took Rochester in 1215, using the fat of forty pigs. The CATAPULT and trebuchet were mainly used to break BATTLEMENTS, kill defenders and wear people down.
Heraldry was a recognition system
Once a man's face was inside a closed HELMET, nobody could tell who he was. HERALDRY solved it: a pattern on the SHIELD and BANNER that identified a family at a distance, governed by strict rules so two designs could not be confused. Colours had to contrast with the background, hence the very bold palette.
It became a legal system with courts to settle disputes over who owned which design, and some of those cases ran for years. The vocabulary survives in odd places — the language is Norman French, so a shield is described as being per bend or in chief, and the words on a modern football club badge or a university crest are often neither English nor Latin.
Chivalry and the damsel
CHIVALRY was a code for the behaviour of armed men towards each other and towards the Church — largely an attempt to limit the damage that heavily armed landowners did to everyone else. Its protections applied to people of the same rank, and the peasants whose fields those armies rode across were not covered.
The DAMSEL in distress is largely literary, arriving in the romances rather than the records, and real noblewomen ran estates, held castles under siege and managed the finances while their husbands were away on CRUSADE. The rest of the grid is the fabric of the place: the MOAT (often dry, and as much about stopping tunnelling as about water), the DRAWBRIDGE, the PORTCULLIS, the DUNGEON, the LANCE and the JOUST, and the SWORD. Our King Arthur page covers how the stories were built on top of all this.