The player takes the role of Sgt. John Baker of the US 34th Infantry Division. This campaign covers the Battle of Kasserine Pass, the turning point of the North African campaign, the fall of Bizerte and the Allied invasion of Sicily in 1943, followed by the amphibious landings and defense of the beachhead at Anzio in 1944. Breakthrough adds Italian weapons for single player and multiplayer as well as the British and Soviet weapons from Spearhead. Also, additional British weapons are included, to complete the British arsenal.
Mission 1: Battle of Kasserine Pass and Tunisia campaign
Mission 2: Sicily and Operation Husky
Mission 3: Invasion of Monte Cassino, Battle of Anzio and Monte Battaglia
The appearance of Italian soldiers in the expansion pack made Allied Assault the first Medal of Honor game to feature Italian soldiers.
The expansion pack has been noted for its historical inaccuracies and anachronisms, and received lower scores than Spearhead or Allied Assault.
The 82nd Airborne soldiers that appeared in Mission 2 wear 101st Airborne arm patches and share the same face texture; this seems to be caused by a developer oversight.
If you go to any fan-made level, it is possible to see the statistics with the picture that it was impossible to see before. Most likely, these statistics should have appeared after the mission in Italy, but given the fact that after the mission in Italy are credits, these statistics are not visible.