Here is the full list of all 12 Breach achievements worth 200 gamerscore.
Earned the top rank of Commander Tier 3
Get 100 kills playing the Recon class
Earned the rank of Commander
Earned the rank of Lieutenant
Earned the rank of Specialist
Get 100 kills playing the Sniper class
Get 100 kills playing the Gunner class
Get 100 kills playing the Rifleman class
Earned the rank of Operative
Get 100 kills playing the Support class
Earned the rank of Agent
Successfully crushed 30 enemies with structural collapses