Planetside 2 has taught me a lot about leadership.
In the game, which is an MMOFPS that plays a little like the Battlefield series, most people don't play as leaders. However, you can lead either a squad of up to 12 players, or a platoon of 4 squads, meaning up to 48 players. You fight in a 3-way conflict with up to thousand players on a given map.
Staying positive is incredibly important. You can't always win, but you can usually find a way to have fun and leave your players happy even after a loss. This is equally true of real life: winning the fight immediately in front of you might not be possible, but in the long term it's better to find an objective you can achieve than to keep forcing your team to attack a problem they can't solve.
Team-mates who have a microphone and communicate with you are incredibly important because they give feedback on your choices and call out things you've missed, but you might only have a few in your platoon, or even none at all. People won't always communicate problems or opportunities to you unless you've carefully nurtured an environment where they feel safe and get rewarded with social approval for speaking up.
If you keep throwing your platoon into fights they lose, they'll become disengaged, and either check out and stop following orders, get upset and play worse, or just leave. You. deal with this by giving them some easy fights where they outnumber, outflank, or outskill the enemy. In real life, after a tough few weeks, throw in a day off or a sprint that's deliberately light on cards.
Speed and agility are incredibly important, as is planning a couple of steps ahead. If you have players who are just a bit faster than others, who have just a bit more initiative, you can go straight from fight to fight with no downtime and without time for the enemy to respond. If you pre-empt enemy manouvers, you can create options for yourself at very little cost that save you significant time in the future. Similarly, adding kill switches to new features, or refactoring your error handling to give more info, can save you hours of downtime. Already having feature X under development when a competitor announces they're working on it can let you quickly respond to market demand.
You should remove actively disruptive players as soon as possible to protect your well behaved players. Trolls, racists, those with anger management issues, or just extremely negative players should be immediately told off, and kicked out if they don't stop. If you don't do this, you'll lose your best players trying to retain your worst.