The first level where you have a Tech, Marine, and Medic accompany you is the level this is found on. The Marine's name will be Corporal Mahler (Who gives the medal). They must survive in order to receive this, and the level is two levels long. This can be easily done on private, though it can be done on any difficulty, it's just that private is the easiest and they seem to die the least. Just run through the two levels and you will receive the award as long as no one dies. After you meet up with Rhodes, you will receive the award.