You lost because you refused to adept. You keep pumping out the same units that were just getting killed over and over and over again. You had the chance to crush him in the start with a few hit and run attacks but you didn't scout him, you just set in your base with about 10 units that could have leveled his refinery in seconds.
Even later on when when you had the battle at the bridge and he backed off you keep running after him even when you had secured your bridge crossing with infantry. Yes, his grenadiers would have eventually thrown those buildings down but you had enough time to him his refineries and his totally undefended base. He would have had to brake off his attack and go back.
You have so many units to chose from as Cartel yet you keep building the same ones over and over again. Just one art would have devastated half his grenadiers at the later battle at your refinery and you could have even shot him from the comfort of your own base.
Also, you ruined many of your own units by continuously sending them over the roads one by one. On top of that the pumas were shooting you with long range missiles which do MUCH more dmg then their autocannon yet you keep your tanks at long range instead of closing in and taking the pumas out. I can only guess that you though those pumas full of grenadiers so you didn't want to get into range. But the thing is the pumas missile range is shorter then the granadiers range.
