I've long held that the correct term for the concept frequently called warlord or marshall is "Fighter".
It's simply the "smart fighter" or "charismatic fighter" archetype. It's a bad idea because it silos away from the fighter abilities that should be part of the fighter's core idea. Every fighter eventually should reach a point when they are no longer just a grunt on the field, but a legitimate leader of men in battle. The concept of a warlord or marshal is simply a fighter that is especially good at that, even at low level. It should be a fighter subclass, plus a few feats available to enhance anyone that wants to take that 'battle leader' sort of role.
I disagree with this.
I'm a big reader of history (both real and fictional variants). One of my favorite pieces of historical fiction is Romance of the Three Kingdoms. Each kingdom had numerous commanders, ranging from those who could only fight, those who could do both, and strategists.
Xu Zhu was an example of the former. He was nicknamed "Tiger Fool" for a reason. He served Cao Cao and generally spent his time nearby as a bodyguard. He was, in emergencies, sent to the front to go kill enemies. That was it. This was someone who wasn't going to command anyone or anything, he was in emergencies going to kill those who could for the other side.
On the opposite end were people like Zhuge Liang and Lu Xun. The former is portrayed as an over-the-top genius in the books, but in real life was just a good strategies. A good strategist was worth 10 commanders, supposedly. He wasn't going to personally kick anyone's butt, he wouldn't have been capable of it. Lu Xun was a young "impractical scholar" yet his forces defeated Guan Yu's (a capable commander and the second-biggest badass in the book, and a badass in real life) in combat. Guan Yu was literally worshiped as a demigod later and is a pretty good example of a real-life "high-level fighter". Why did Lu Xun defeat him? Because Lu Xun was smarter. Knowing how to use a dragon saber is not the same thing as knowing how to command.
The most valuable were the commanders who could do both very well. Cao Cao and Liu Bei called these guys "Tiger Generals", although only Cao Cao's guys were really worth the title. (Liu Bei just called his best five fighters "Tiger Generals", and only some were good commanders.)
If this kind of thing needs to be attached to the fighter class, then I think those class abilities need to be based on Intelligence and Charisma. Some fighters simply aren't going to be that bright, and will be very good at roles such as bodyguards and battlefield assassins. That's fine. I have a problem if such a fighter can somehow become good at command just because they've got some levels under their belt. I have less problem with a fighter who has the
potential to be a good commander, but perhaps didn't follow that path (didn't take those feats or didn't take the commander multiclass and/or prestige class) early on.