The object here is to stop fuel trucks from leaving a depot and then capture the depot and hold it for a few minutes against furious counterattacks.
It’s a difficult mission, particularly if you want to get the gold medal, which requires killing all fuel trucks but one, i.e., you may let the first one go but you must kill all the others. (It is possible to stop even the first one, but that cannot be done every time.)
To achieve this, you have to move immediately north with your starting units and defeat the volksgren and pzfusilier squads at the nearest point to cap it. You must then move without delaying more than a minute or two to the next point, where you will deal with (at least) a panzerfusilier squad, a fallschirmjaeger squad, and a Luchs light tank—not easy. Then you’ll have to move north and get in the way of the second truck, killing it before it leaves the map—and if you go north of the river to do that, you’ll have to tangle with more German infantry. Soon a third truck will come along, now guarded by a Luchs or a Puma or a flak-HT, and you’ll have to deal with them. As you do this, you need to build up your forces. Eventually you’ll move on the truck depot, use artillery on HMGs and/or Paks, then put LMG- and schreck/bazooka-equipped squads in buildings around the depot point, then take it, and finally hold it for a couple of minutes against infantry + Luchs/Puma attacks.
Only bazooka/schreck-carrying Rangers or a vetted Baker Co. can manage this, the latter with difficulty because of the lack of anti-vehicle power early on (Baker must give its squads bazookas asap if it doesn’t start with a tank or TD).
Note that, even before you take the depot/fuel point, but after you have taken the point closest to it, the CPU will tell you that German units are scrambling to defend the fuel point—and indeed it will keep creating German units, mostly Luchs tanks, scout cars, fallschirmjaegers and panzerfusiliers. These units will just keep flowing in from off-map to accompany the outgoing fuel trucks. If you’re in position to wipe them all, you can build up a lot of experience points by just sitting there and doing that for a while, instead of taking the depot. You can also accumulate a lot of casualties.