When my boosting group of 4 people
ran through the maps for WWII Victory Medal, 3 out of the 4 of us unlocked the achievement. This is the process we followed:
1. Only one person went at a time. I started on Remagen and went through the maps. I didn't do Avalanche because I had boosted many times on there before. However, the achievement didn't pop after doing the 5 other maps (though American
did), so I did Avalanche once more and got my achievement.
2. The second guy had never played the game before at all. We ran through all six maps and he got American and WWII at the same time.
3. The third guy had boosted kills and objectives before, like me, and probably had only played on Avalanche. We went through all six maps and his achievement popped.
4. The fourth guy had tried to get WWII Victory many times before. He had all other achievements except it. We still ran through all of the maps, hoping the fact that we all had it would help, but he did not unlock the achievement.
So in theory, there are several factors that influence your chance of receiving this achievement.
1. If you played the game before the update and received the American or EAM achievements, you probably won't get it. This means that you should try to get WWII Victory Medal at the same time as American and EAM.
2. Try to boost WWII Victory Medal earlier rather than later. The three people who got it in our session had all started boosting the game in 2012 and had never touched the multiplayer previously. We also had only boosted kills and objectives previously, meaning we never played the game with randoms.
3. When boosting the achievement, do each person’s six maps in a row.
4. Do everyone’s turns in the same session, with no one leaving to go to the Xbox Dashboard. This may well tie into Shin Gatsurai’s theory
that having other people with the achievement in your games increases the chance of it popping.
5. For the actual winning of matches, you only need to capture all of the flags in Objective Airborne; no kills are required.
I hope this helps some more of you get this very elusive achievement. If you have any questions, please PM me!