The only rl that I know of where the player controls a group, more like a party, is in an obscure game called 'Wizard's Lair'. But, the party moves on one tile & its only effect is in combat.
This summer, I began development on a game with Wizard's Lair as an influence. In my game the player manages a small army of up to 45 soldiers. The soldiers' ai uses flocking algorithms, ie steering behaviour to move. The player leads them and can issue orders, regarding their squad formations & behaviour. In this way, I can achieve 'massive' battles with like 80 goblins versus the players army.
It is definitely a cool idea, which is why I am exploring its possibilities, but it is more difficult to manage not only from a programming perspective, but also from a game design/balancing perspective. In my scheme, the player gives orders to the squads and the ai acts somewhat autonomously based on the player's suggestions.
I hope to release this someday & I think I am getting close, but also I think I may be the master a vapourware so who knows....
Also, dwarf fortress seems to implement squad based defensive combat when defending the fort in fortress mode.