You are definitely short on the 'Infantry Dept'.
Since I had never played this game before, I was mezmorized by wanting the Iron Beasties and the Air support first and formost, excluding the need of Infantry and artillary. I paid for my mistake in judgement, and lacked those units in my combined attacks as well. Without them in Tutorial 5, it will become a wasted slug fest on your part, and eventually grinding to a halt, falling short on your objectives.
I replayed the Tutorials through 3 times to really get a feel for how things work...I am a
slow learner, but it sure makes a difference to gaining 'Decisive over Marginal' having practiced so many times with the tutorials, though I have only finished the Poland scenerio on the campaign so far.
I bumped up to Field Marshall for the Campaign, found taking Poland not too bad, gaining a decisive; but felt a little sloppy in my attack on Warsaw in the end. More than likely I will have to bump down to Colonel, until I get a tad better with my coordinated attacks against enemy AA and Artillary, where I am still lacking confindence somewhat.
Like others have said, restart, and rebuild your forces to include Infantry, will save you alot of frustration and heart ache.
: < )