Attacking with Armies
An army can attack another army, a castle town (or settlement in Fall of the Samurai), or any building on the map. Buildings will be raided and damaged, but cannot be occupied or garrisoned. An attack on a castle town will result in a siege taking place. If the target is further away than your army's movement extent will allow, it will take more than one turn to reach it and launch an attack. Once an army has reached its target the battle panel will be displayed, prompting you to fight on the battlefield, resolve the battle automatically, withdraw or lay siege (when appropriate).
Click here to view a video tutorial about this subject.
Besieging Castles
In order to gain control of a garrisoned and fortified castle town (or settlement in Fall of the Samurai) it is often necessary to lay siege. During a siege your troops surround the castle and can either attempt to starve the defenders into capitulation or launch a direct assault. The besieged force may also choose to sally out to meet you on the battlefield, but be aware that defeating them will not automatically result in the surrender of the castle to you. Victory in a siege turns ownership of the province over to your clan. You then have the option to occupy peacefully or loot the castle. Looting provides a cash lump sum but carries a greater penalty to public order (and indeed your daimyo's honour) than occupation alone. There will also be public order issues if the new owners of a province are of a different religion to that of the populace. Click here to learn about sieges on the battlefield.
Click here to view a video tutorial about this subject.
Resistance to Occupation
Following the conquest of a province there will continue to be a degree of unrest in response to the change of ruler. This is called "resistance to occupation". It declines gradually over time, but never totally disappears, so it is wisdom to leave adequate garrisons behind and manage taxation carefully.
Ambushes
An army positioned in a forest can sometimes launch an ambush against a passing enemy. If you choose to attack, your forces can be split between each side of the road and the enemy force will be deployed in marching, rather than battle, order. The enemy army will not have the opportunity to move their units in any way until the battle starts, so deploy carefully to cause maximum confusion and disorder. If you decide not to launch an ambush, the army will pass without being alerted to your presence. NB - If you are playing battles on hard or very hard difficulty and are ambushed it will not be possible to issue orders when the battle is paused.
Reinforcements
If it is possible for one army to reinforce another this is indicated by a yellow line that connects them when you mouse over either army. If a red line appears between two armies it means they are enemies within each other's zone of control.
Click here to view a video tutorial about this subject.
Port Battles
In Fall of the Samurai if you attack a port whilst there is a fleet moored this will result in a port battle. This is effectively a siege, where the docked fleet is the defender, bolstered by coastal defences.