Using the Kingdom of SwadiaEdit
The Kingdom of Swadia has a very strong and balanced troop tree, however, its location in the center of Calradia means that there is no such thing as peace. Expect to be always at war with one or two other factions. Even though Swadian units are great for the offensive, in the beginning of the game, it's best to be on the defensive, otherwise you'll lose many castles and perhaps even a town (in most cases Dhirim). But if you are strong enough to withstand the attacks and able to break the Sieges outside the castle with Knights, the Kingdom of Swadia will be nearly unstoppable.
When using Swadian troops, it is advisable to position your crossbowmen on a hill just in front of your cavalry and spread both of them out, then place Sergeants behind your cavalry in tight formation. Do an opening charge just to confuse and mess up the enemy, then rush in your infantry to help. Do not disengage your cavalry until your infantry are all in the fray. The Knights will mindlessly try to run away when disengaging while getting attacked from behind. Once your Knights are out, charge again from a good position with couched lances. This will destroy the enemy almost instantly and your Sharpshooters will pepper the enemy at all times. Alternatively, you can simply amass Swadian Knights which can crush any foe on a flat battleground (which is easy to find in most places). This tactic, however, will be very expensive, as knights cost around 50 denars every week (depends on leadership).
Another strategy is to have your archers hold, infantry charging, and your cavalry following. Lead the flank with your cavalry, while your archers are shooting at them, and infantry directly attacking. Get behind them with your cavalry, then have them charge. Once they hit, regroup and do it again.
Swadia may not have archers, but their crossbowmen are superb, nearly a match for the Rhodok crossbowmen. When defending a castle, position your sergeants on the walls to defend against foes using ladders or siege towers. If you are short of sergeants, Knights also make a good fill-in infantry. Order your crossbowmen to positions where they can get clean shots into the sides of enemies advancing up ladders or siege towers.