Objective: Establish and maintain a supply line for 2 turns
Turn Limit: 5
Echelon Limit: 1
Recommended Echelon(s): AR/SMG
Why yes, this IS one turn movement each turn the map. Quite literally, all you need to do is move one node per turn to the rally node. No, you don't have enough time to go resupply. Thankfully you can kill all but one enemy on your side of the map. Do note that the tarantulas can move, so you want to kill them. Good thing that doing so doesn't impede you at all, just means you're shoehorned into going to the right to get to the rally node.
There is a big scary Dactyl echelon that's murderizing the Sangvis units on the right side of the map, but don't worry about it. By the time it's near you, you'll have the supply line up and running, so you can just leave. It won't take the rally node away from you.
Video of me clearing this map