If you're like me and dislike the gameplay and only want to complete the missions as fast as possible, here's what you do:
1) Choose a lineup with high speed, minimal armor, and low HP. You want to get into a fight ASAP, and lose that fight ASAP. I recommend a lineup consisting of the following: AMX 50B, B-C 25t, Leopard, Grille, AMX 13 105, Rhm Pzw, and B-C 155 58.
2) The defensive structures don't matter, but make sure not to pick the MRL. You might accidentally kill an enemy tank with it and that'll just slow down the game.
3) Pick a spawn point closest to the enemy base and put all of your tanks there. The defensive structures can be placed anywhere, they're not going to get any action anyway.
4) Once the game starts, select all of your tanks and move them directly into the enemy cap. They'll charge there, take whatever shots they can along the way, and get annihilated. (Note: on an map like Airfield where the cap spot has a huge number of structures to hide behind, it's probably better to have them charge to a spot just outside the cap so there's an open field of fire onto your tanks.)
Using this method I've been able to get games as short as 1:30, with the average game being over in about 2:00 or so. Do this 6 times and you'll have your two missions done in under 15 minutes. Enjoy the art of "strategy" folks. 🤣
Source: https://www.reddit.com/r/WorldofTanks/comments/u9ohdq/speedrunning_the_art_of_strategy/