I don't think I understand the game properly.

Hi everyone. 700 rated king here.I don't think I understand how to play properly as I seem to be making the same mistakes over and over.My capture phase always seems to do better than the opponent but when it comes to combat I get slaughtered by about day 15 most of the time. I know about capture strategy but when it comes to positioning combat units to come out on top of encounters, I'm absolutely hopeless. I don't think my selection of units to build is bad either. I think I'm perhaps playing too loosely with attack units and leaving them exposed which means I don't retain any kind of structure. Here's a replay link to a battle which I thought I started well but I was soon destroyed as usual. Do I lack a complete understanding of the game?https://awbw.amarriner.com/game.php?games_id=1141782&ndx=0 (I'm Orange Star)