Abused the horse on this campaign and in part of the next campaign as well. Wiped out areas without even firing a bullet. A little horse power.
I found this the easiest method for most all of this campaign, after the first section. Run everyone over and keep moving for the most part and hit all the objectives.
See the video for more clarification. This made these sections easy.
For the Armored Train section I just ran circles around the village while throwing both anti tank grenades at the train. Backtrack and grab one of the horses. Be aware that there are two health bars to watch. Yours and the horse. Doing laps around the village regenerates health plus your anti tank grenades. They take some time to recharge. You get two per charge and thats the max.
0