Halo Reach Nightfall issue

[MorganL4]

Okay, So I just beat halo reach level 4 ( nightfall) on legendary (solo). Now I had work today so I couldn't finish it last night when I was playing so I started at rally point alpha. I was trying to figure out why I didn't get the achievment for it. The only two possible things that I can think of are:

A I started at rally point alpha, and to get the achievment I need to go from start to finish OR

B I didn't keep the other soldiers alive and thus did not complete that objective. (less likely but possible)

anyone know for sure what the reason is?

 

[JokerboyJordan]

Yeah same happened to me on Sword Base. You have to start from the beginning. It sucks I know but it's generally easier the 2nd time

 

[Polaris19]

Yep, you gotta start the mission from the very beginning.