Tom Clancy's EndWar

This trophy description may be a little confusing. To capture a Capital city, you must win a Conquest, Assault and finally a Siege mission consecutively. If at any point you lose one of these missions, you will revert back to the one before it. For example: If you lose the Assault, you will have to start over with the Conquest on the next turn. For this trophy you must capture a capital by not losing a mission. That means winning the Conquest, Assault and Siege mission types consecutively. The key here is to save when you win and reload your save when you lose. Do this on Normal as trying to capture a Capital on a higher difficulty is very, very challenging.

As far as strategies go:

1. Conquest: Use your Deep Strike ability to remotely deploy Riflemen directly to an enemy Uplink. The idea is to keep the enemies moving. By the time they've reached an Uplink, you're already capturing another.
2. Assault: Create a small task force of two tanks, a transport and a Gunship. Keep these units together and move them around the map, systematically destroying enemy units.
3. Siege: Deep Strike a Rifleman unit to the Critical Uplink to capture it. Use your Gunships to spot units at long range and then nail them with artillery. Gunships are also good to quickly take out enemy Artillery. Slowly move up a squad of tanks and transports to the critical Uplink to help support the Riflemen. Hold out for 5 minutes to win. One thing to note here is that the enemy does not get reinforcements right away, it becomes significantly more difficult to win when the reinforcements arrive so be quick and be efficient.