For triumphantly entering a city, play the Elven War Theme from Two Towers (especially if you really aren’t supposed to be in that city 
)
For a battle in an already-fought-over wasteland, play something powerful from Mozart’s Requiem such as Rex Tremendae.
Read the OP, specifically his second choice.
oh, c’mon now…
Flirtin’ With Disaster
Train, Train
Highway to Hell
and finally:
‘Tanks for the memories…’
Funny all the times I spent in tanks this never came up. Too busy listening to the radios.
When I was in college I taped “War Ensemble” off of my CD to listen to in the car, but I accidentally had the tape on high speed. When I played it, it was slowed down to half speed and everything was dropped about two octaves so that Tom Araya sounded like a Balrog eating a mountain. It was so heavy it cracked the foundation of my house.
“One” by Metallica
What about the A-Team theme music?
And I’d suggest that anything by Metallica should also be off of their S&M cd, for that added touch of elegance and class. We’re not savages, you know. 
The Theme from Rocky is good.
Tina Turner doing The Bitch is Back from the Two Rooms CD is good for the lighter moments of tank combat.
Same here, really, until Maj. “Batman,” our S-3 (named because he thought anyone “infantry” was automatically a superhero, and because, well, he was fucking batty), started constantly calling up requesting asinine status reports every 15 minutes. The thing is, our “encoded” sitreps took about 3-4 minutes each to transmit, tying up the net, and you basically had to do it all over again ten minutes later.
After doing this about 3 or 4 times, all the command tracks in the two tank companies suddenly developed vague yet persistent commo problems.
It finally got so bad that our CO and Bravo Co.'s CO went to the old man and basically said, “When you hear us shooting, you’ll know where the bad guys are; so please get Maj. Batman off our ass.”
Brutal Planet by Alice Cooper.
Ah, that’s just because you guys didn’t have iPods! 
Vivaldi. The Four Seasons. Just for the incongruity.
Just time any exciting moments to coincide with Winter.
“Sir, the enemy is closing in.”
“Tell them to wait a couple minutes until the next movement starts!”
“… yes sir.”
I tried twice to enter “The Imperial March” from The Empire Strikes Back, but the hamsters were down and it wouldn’t lert me. Then somebody else stole in and said it.
(grumblegrumblegrumble)
In lieu of that, how about Weird Al’s I’m Drivin’ a Truck (with my High Heels On)
It occurs to me that for a pitched battle, Liberi Fatali would be another excellent choice, especially if you expect to find yourself abandoning the tank to duke it out mano-a-mano against the enemy with swords.
Mmm. Not a pretty picture. I’d take Kipling’s advice about fighting in Afghanistan before abandoning my tank to anything less than catastrophic fire to “duke it out.”
Tanks come in 4-packs, ya know (at least in the U.S. Army they do). That’s a lotta whoop-ass to step off in; as Uncle Jun told Tony is season 1: next time, come heavy, or don’t come at all.
I’s hads me some buddies to catch my back.
Portions of the sound track to Dead Again would work, and so would Star Trek: The Wrath of Khan.
The Spanish Legion’s “el novio de la muerte” (Death’s Lover) works well with anything involving guns and the possibility of explossions.
Rammstein has quite a few that are booming enough.
The “wait for supports” advice or the “roll to your rifle” advice?