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6.4 Morale
Army morale has a disproportionate effect on battle outcomes. A small high morale army will most of the time defeat and force to retreat a bigger low morale army. If you hover the pointer on the morale bar of an army that is not fighting it will tell you how much morale the army has. Another indication that you are lagging in morale while fighting is if during battle your troops morale goes down faster than your enemies troop morale. So how do you get high morale troops? Easy enough, have a high Land technology level, set your DP sliders at offensive, land, quality and free subjects, and have your army at full maintenance. You will have a very expensive high morale army. Be aware that army morale cannot go over a certain maximum, so some of your bonuses might be redundant after you reach a land tech level high enough. You also get a bonus for being shiite, hindu or counter-reformed catholic (CrC), or for claiming to be the sole defender of your faith (DoF, not for reformed or CrC). Also the military skill of your monarch will affect army and fleet morale. And finally do not go bankrupt, your armies will be at half morale for 5 years. For your fleets is the same except that the only DP slider that affects morale is land/naval, and no religious bonus applies. Although it seems illogical, attrition has no effect on morale.
Regarding troops, your base morale increases every three or four technology levels reaching integer amounts at levels:
Level 0: 1.5
Level 4: 2.0
Level 11: 3.0
Level 21: 4.0
Level 41: 5.0
Level 60: 6.0
A 100% maintenance will add +0.5, while the deduction from 50% maintenance depends on tech level and goes from 0 at level 5 to -1.0 at level 60. The DP factor is smaller than some people think, and goes from +1.2 when all the sliders are fully favorable, to -0.7 when they are fully desfavorable. At the beginning of the game most countries do not have a significant DP bonus, and it might take you 150 years or more to max this bonus out. The religion factor is +0.5 for shiite, hinduism and CrC. The monarch factor goes from +0.25 to -0.125, and DoF gets you +0.15. Morale cannot be higher than 7.0.
Regarding fleets, your base morale increases every eight to ten technology levels:
Level 0: 1.5
Level 17: 2.5
Level 31: 3.0
Level 42: 4.0
Level 49: 5.0
And you can boost it +0.5 with the naval/land DP slider at 0. All other factors are similar to land morale.
An army with low morale (new army or recently defeated) will increase its morale every first of the month until full. Let your armies recover morale before facing the enemy, but do not allow the enemy to recover morale. Another way of increasing morale is by winning a battle. But an army undertaking a siege does not increase morale after a succesful battle. This allows to defeat a siege by successive attacks in the same month to reduce the morale of the enemy army until it can be defeated due to low morale.