I will make a slight variation to that stragety if i may. What i did was i kept getting heavy troopers and turrents. So they couldnt get by my defense. After they attacked with an ATAT and like 4 ATST's they didnt attack much any more. I kept getting more hvytroopers and i sent them to the right after a swoop. Let the swoop find the artillery there will be about 4. Then i sent my ATAT to the right to take out the anti air defenses. Then i brought it right back. The anti air and anti infantry defenses should be on a hill. I repaired the ATAT and kept it ready. Then i sent in the ywings to bomb the artillery and sent it the hvytroopers to take over the turrents. I had about 20. Move your way up the left side and there will be a base. First send in Ywings to bomb the walkers(Not the Turrets) then send in your men to take over the turrets and command center.
Now that you got this done youve almost won. All you have to do is take the ion cannon. It is guarded by 4 artillery and 4 anti infantry turrents.(In other words your guys dont have a chance to just rush in. I first sent in 4 empty troop transports to take out 3 artillery. The last one is on a hill in the back and your guys wont get wasted by it. Then i sent in the ATAT walker to take out the turrents. Then send in hvytroopers to take over the ion cannon, bring dellis in and your set. (It should be noted i didnt get the imperial base just north of mine on this mission. I tryed at first and relized it would be eaiser to just leave, cause it wont do much later on.)
Hope this helps. Im stuck on Redemption at arbidon.