I have a question about loading up checkpoints such as Alpha, Bravo, etc. Long time ago when playing Halo 3, I loaded up a checkpoint (Bravo) to complete a mission, after doing so it did not count as completing the mission. It seems understandable, but in Halo 4, I am trying to go through Infinity without loosing a single marine for the achievement. It would be easier to load up the latest checkpoint where you finally find the marines, but the achievement says “complete mission 4” does this mean I have to start at the beginning of the mission over and over every time I mess up (I know I could just kill myself to load a checkpoint but sometimes I am unaware of a marine’s death) or can I simply load back to the latest Alpha checkpoint and get the achievement from there?