Mega Noob here - Why can I not overrun my enemy?

Why does my 79 to 8 not result in a victory? I understand a well-fortified enemy is hard to overcome but I figured a 10 to 1 would be an easy win.

Full disclosure I have like 4 hours playing this game, so still learning the ropes.

update: this is what happens when I click on red attack button:

The year is 1940. I am (strong) allies with basically all of Eastern Europe including USSR so I am only fighting on western front.