Military

Military (Page 1)
The combat mechanics in the vanilla game runs quite well and is pretty enough for EU4's gameplay, so CU changes little of it. Instead, CU makes it much more balanced by adjusting almost all details: Military technologies and many units have been rebalanced, allowing early fire units to appear(eg:Longbowmen). All military idea groups have been reworked, and many countries now have unique units whose name are drawn cyan(Thanks M&T Mod for this cool idea).

The supply limit calculation is now totally reworked, turning the logistics into a major aspect of war, and making the fort an important role in both defensive and offensive operations.

Switch to the supply limit map, you will see that provinces without a fort now have a much lower supply limit than those with one. Land attrition in provinces with a bad climate and terrain has also been increased.

Manpower (Page 2)
The new supply system makes the "human sea" tactic much more risky, especially in cold or desert areas. You may suffer tens of thousands of casualty even before encountering your enemy. If you want to avoid this, please devide your troops, improve their quality, build a fort chain from your army's station to the frontier, stay home or in a captured fort during winter. If you have to attack in winter, don't merge your troops too early.

All military idea groups are now completely balanced, so choose the one that you need the most.

Militarization (Page 3)
The Militarization mechanic introduced in 4.2 stimulates the gradual professionalism and militarization of your country. Each state province generates Militarization Point which is affected by military buildings and literacy. Militarization Ratio equals to the sum of MP divided by the total development of your state provinces, which is the main factor of your country's Militarization of State. Military Ideas and Conscription Law also contribute to the growth of Militarization.

Militarization of State boosts your army's morale and discipline hugely, allows more military leaders to spawn, and keeps your country's army tradition high even after long time of peace. However, high Militarization also means that it is more expensive to recruit and maintain your army.