a few question about combat in HW2

just played two games in HW2 one where the enemy players were kinda derpy and didn’t do anything, and another where I was steamrolled. I love the progression system. it gives a really nice Age of Empires vibe ( a la the late Ensemble Studios may they rest in peace). but unlike Age it feels as though he who has the better equipped army wins.
I’m no saying that I didn’t deserve to be steamrolled, but one of the main reasons I avoided Halo Wars 1 was because the limit of the strategy in that game was rush build an army, select all units, and go on a murderous rampage to win. That’s not RTS and it isn’t deep or rewarding.
I’ll probably jump in again tomorrow of the next day to experiment but I had a question for the people that have played more games.

Should I be dividing my troops and placing them in strategic locations? I lost pretty hard when I tried to flank an enemy with one half of my army. I got around to the back entrance to find that my troop was decimated. I’d concede that I underestimated the time I had to work with but I’m also worried hat attacking the back of an enemy yeilds no benefit hich would really be a let down for the game.

So, what other set ups are viable that aren’t the murderous horde approach?