The 110th Cadian regiment and the Order of the Ardent Flame were teamed against the Ork Blood Axes and the Black Legion. The map was split into two team-sided halves, with two choke points on either side(one for each teammate on each team). Bolter bitches got to play with the Orks, while we were stuck holding off heretic attacks.
Actually managed to get a decent enough force at my chokepoint that I was able to flank an Ork breakthrough and support the Sisters, then turn my troops right back around and flank a Chaos incursion that tried to take advantage of the troop movement. My whole force was nearly wiped out, but the traitors were pushed back hard enough that I had time to rebuild with several Kasrkin squads, Leman Russ and Thunderer/Laser Destroyer tanks, and a battalion of Basilisk artillery. Not even the daemon-possessed tanks that the heretics had spawned were a match for the armor of the Imperium.
As I was slowly grinding traitors beneath the tracks, I saw that the Sisters of Battle had already punched hard into the Orks' territory, closing in on their base. Even after they lost their main settlement, there was a Big Mek that managed to keep fighting for several minutes.
I stopped outside the Black Legion's main base, shelling it with artillery. While I probably could have charged forth and burned it to the ground, I built up instead so I could deploy a titan, just for giggles.
Dawn of War: Ultimate Apocalypse.