Love the idea. What about making these alternate uses of action surge? Might need to buff them slightlyMy thought is that thanks to all their training and experience, all fighters should have a baseline ability to assess the battlefield situation and give their team a tactical head's up at key moments. Not with the more specific commands of the Battlemaster - no need to step on their toes - but in a more general sense.
"This doesn't feel right, guys...be alert!" (advantage on initiative)
"Find cover, NOW!" (half AoE damage)
"Reform/fall back!" (instant half movement with no opportunity attacks - this would happen right away during the fighter's reaction, which I think would be unique and cool)
I'm kind of having fun thinking of these - offer a few more! And I think this would be really fun and fit the fighter flavour really well, making them more than just "person who fights good!" It would reflect that they are students of battle, qualitatively different from raging barbarians, devout paladins, and self-disciplined monks. I'm going to playtest it at my own games.
But, you know, I'm just spitballing. Suggest something better; Chaosmancer has a thread packed with thoughtful fighter ideas.
I stand by my contention that fighters kind of feel like they've lost something, with mastery belonging to everyone ("if everyone is super, no one is.").
"Be alert!" +10 to initiative
"Find cover, Now!" Evasion for all allies on the AOE, If you already have Evasion, gain advantage on the roll
"Form up!" Full movement with no opportunity attacks
And a few new ones, including a few out of combat options
"Strike!" All allies can immediately make a single weapon attack w/o a reaction
"Listen!" Add 10 to a persuasion or deception roll made by your or an ally
"March!" Increase daily travel speed by 50%