Through all of history generals and kings almost always stayed back in order to strategically direct the battle.
Besides Alexander the Great, there weren't many.
Oh, wait. There were a few.
Off the top of my head: King David, Queen Zenobia, Phillip II, Darius III, Xerxes, Leonidas, Lysander, Aegisilaus, Gaius Maurius, Julius Caesar, Pyrrhus, Marcus Marcellus, Hannibal, Jugurtha, Mark Antony, Magister Militum Flavius Stilicho, Edward Longshanks, Robert the Bruce, Alaric the Bold, Erik the Red, Attila the Hun, Krum the Horrible, Vlad the Impaler, Ragnar Lothbrok, Khalid Ibn al-Walid, Genghis Khan, William of Orange, George Washington, Robert Rogers, Andrew Jackson led an army of goddamn pirates at the battle of New Orleans, Stonewall Jackson among dozens of his contemporaries -- in the Civil War, generals on both sides literally stood in a firing line with their troops -- Custer, Patton, Teddy Roosevelt, Nikola Zrinski, General Gavin parachuted into Normandy with his troopers, Rommel ("The Desert Fox"), Ord Wingate, Lord Nelson (and for that matter, damn near every naval commander who has ever lived), Santa Anna, Che Guevara, Charlemagne, and Obi-Wan Kenobi.
In feudal Japan, it wasn't uncommon for commanders and warlords to slug it out one to one on the field, which is what generals and warlords do in the world that I created for my series.
King Abdullah II of Jordan led a combat mission to beat the crap out of ISIS a few years ago after they burned one of his pilots alive. As if that wasn't badass enough, he's the head of his nation's Special Operations Command and acts as their jumpmaster during training exercises; they train side by side with U.S. Special Forces and Navy SEALs and he's out there huffing and puffing beside them at the ripe old age of 53.
Coming in a close second, the Brits' Prince Henry flew an Apache attack helicopter in Afghanistan.
Leaders lead. That's why they're called leaders.