How were medieval Japanese castles defended?

Answer 1

Forget "medieval" when discussing Japanese culture, since it only refers to Europe.

Japanese castles and fortified temples were cleverly designed to prevent attackers reaching the innermost areas of the castle; there were many moats and isolated bastions connected by bridges to other bastions and the entry-way was always firstly by way of these outworks. Each bastion would have its own garrison armed with long "yari" (spears), bows and matchlock guns. Unless the attackers had a good knowledge of the layout of the defences, they could easily become disoriented and confused by this seemingly random series of interconnecting bastions.

These outer defences were all overlooked by the much higher central part of the castle, from which archers and men armed with guns could pick off the attackers from tiny gun ports or square windows fitted with shutters. Deep moats and sheer stone walls prevented the enemy heading directly for these inner defences.

Only after overcoming each outer bastion in turn (and crossing all the defended bridges) would the attacker reach the second bailey (ni no maru) of the castle, where he would be routed through an outer gateway (koguchi) into a "killing ground" - a courtyard or open area surrounded on all sides by high walls with archers and gunners shooting down into it. The only escape would be back they way they came.

An attacker surviving this section would have to penetrate the main gates, which would be heavily defended and strengthened with iron. Even if the enemy got through the main gate, they were then faced with the formidable "keep" or honmaru; this was a tower with many levels of windows and arrow slits, surrounded by its own strong defensive wall.