What Tactics Are Best When Playing the Underdog?

[Chipmunk]

If you are playing a game of MBT where the opposing country has a marked advantage in equipment or capability to you are there any tactics that can help offset this? For example in a 2007 US vs Iran matchup the Iranians don't have a single weapon that can penetrate the front of an M1 Abrams. another example, in the 80's the USSR can't see through smoke whereas NATO can. Is there anything that can be done if you are playing the underdog? Would it be a good idea to go for quantity and buy a lot of cheap units hoping you can swarm the enemy and get flank shots?