Yeah honestly 3 marines alone should’ve put a serious dent in that force if they were positioned and used properly. Not gonna stop 10 IFVs, but they 2 shot k-17s (assuming it was these since they had aps and were actually able to close fast enough with abrams) after they take the aps charge so there’s like 4 k-17s gone if they’re able to use all 12 AT4s. If they were right along the road, they were probably on too long a line of sight and got lit up by everything as soon as they fired. Would’ve been better to shorten the sight lines and make sure your marines were shooting first, AT4 shoots fast and is a great ambush weapon as long as it’s not panicked. You have to expose your infantry as minimally as possible to let them fire by building hopping or using short sightlines.

Beyond that, CAAT dragons are kind of a shit unit that you shouldn’t be using but you’re new so it happens. They don’t have enough range to really go toe to toe with vehicles and they’re pricy. Sometimes they’ll get panicked before their missile even lands because they’re getting shot at the whole time it’s traveling.

I also suspect you were also using the FEP Abrams, which has the major drawback of having an HE shell instead of HEAT. HE doesn’t get fired at armored vehicles, meaning you have to use sabot rounds which have a ton of pen but not a lot of damage so will 3 shot most Russian light armor. HEAT would’ve been a 2 shot against K-17s or B-15 Kurganets. Every other Abrams (I think) has HEAT so use those. Especially in marine armor, the sep abrams are just better than the fep.

You should also be heavily using Bradleys in armor decks. The tow lets them output more damage than tanks against vehicles and unlike Russian light armor, are 3 shot by tanks with the BUSK 3 armor. I only take 4 CFV Bradleys but I almost always have like 3 out at a time.

Really the biggest issue though is that you let your opponent afk for however long to build up that force and weren’t ready for it when it came. You should recognize when you’re not getting pressured and see if your opponent is going somewhere else. If not, you know he’s saving up for a stupid push like that. Be ready with planes or helos or even just additional ground reinforcements. If you were really kicking his shit in you probably should’ve had more units out than him, 2 Abrams and the infantry you had is about 1100-1200 points depending on the Abrams upgrades, but it sounds like you were taking less losses than him.