Veteran of Midway
Complete all single player missions
[Single Player] Beat the US Campaign. See the mission walkthrough under Hardened Veteran of Midway. However, while these are cascading achievements (you will get Veteran of Midway if you beat them for the first time on Veteran) it is much easier to beat each mission on Rookie or Regular and then repeat it on the harder difficulty. This lets you get an idea for the layout of the map, where enemy forces spawn, how they react, etc.