In world war 2, I'm guessing it was Eisenhower towards the end of the war. Himmler's 2-million command at the final stand of Berlin shouldn't count since it was basically a ghost army, and Himmler himself was not a tenured general. In world war 1, I'm not sure whose army (divided into different fronts) was the biggest, before the inevitable decimation in battle.
How are you defining "command". Why Ike rather than Marshal? The Red Army was bigger than that of the combined Western Allies.
Bradley had close to a million when the Ninth Army was removed from Monty and transferred to him. Well, we have to qualify this to include only field commanders, so Chiefs of staff or Secretaries of War don't count. I'm still guessing Ike since he commanded an entire front, while the Soviets had three independent commanders under Stalin.
The Chief of Staff of the PLA appears to currently be a gentleman called Li Zuocheng. Almost 5 million regulars and reserves under his command. The WW2 Red Army swelled beyond 11 million men at its peak. Can Stalin be defined as its 'Commander'? Certainly wore a uniform, though given his eventual acceptance of delegation I'd definitely be looking for which Soviet Marshal had the largest command.
I am guessing ,Marshal Georgy Zhukov, and Marshal Ivan Konev field commanders, should be strong contenders for the largest number of troops directly in their command. as both approached Berlin, in two groups , because of the sheer size of the Soviet army. Omar Bradley would be my other choice. If I had to bet I would choose Zhukov .
I think it probably has to be Zhukov. Perhaps while commanding all groups in the defence of Moscow the best specific 'mass' of men directly under control? It would take digging about to be certain of figures but he was an active and involved commander of vast armies, plural, throughout the war, beyond his 'executive' status & in a way I'm not sure any historical soldier can quite compete with for scale.
Looks like (from wiki so it's far from certain) that the Red Army fronts may have exceeded a million men at least on paper. Zhukov wasn't the only one to command a Front though. Vasilevsky had 3 fronts and 1.5 million under his command during August Storm. Mac had ~1.25 million under his command during the invasion of the Philippines significantly more were assigned for Olympic under his command, not sure how many were in theater though by the time the war ended. At what point does one stop being a "field commander"?
By the time the People's Liberation Army was in the running I don't think Mao qualified as a field commander.
Chester Nimitz certainly had a few hundred thousand maybe millions of troops at some point? He didn't have the most under his command, but if I can I like to bring up the lesser noticed generals and countries to the forefront
In history is the question. I believe that the answers given pertain to WWII. Is this what the OP wanted? KTK
I think that part was open but under most (but perhaps not all) interpretations of the question I think the answer will be from WWII. The problem is deciding exactly what is meant by the question. From some of the clarification I got the impression combat command was implied so Ike for instance wouldn't count (nor would Marshal or FDR for the US similarly for the Soviets).
I think Model had command of two or three Army Groups at one point between 1943-44 for awhile as other commanders were sacked so he led the troops for the whole eastern front....
Perhaps not the most in terms of troops, but perhaps for largest command (area) and "most on his plate" how about Wavell (Middle East Command) from April-Aug 1941? 1. Outnumbered 8the Army withdraws to Tobruk, avoids encirclement. 2. Campaign in East Africa reaches a climax in Battle of Keren, Italian Army is destroyed 3. Greek Expedition fights the German onslaught and withdraws to Crete 4. British & Indian forces put down a pro-Axis coup in Mesopotamia (Iraq) 5. Battle of Crete 6. Siege of Tobruk 7. Allied forces invade Vichy held Levant, destroy German "Fliegerkorps Irak" bases. 8. Allied forces move into Persia and secure the land route to the Soviet Union.
Most WW1 Armies would have been very happy if they had only been decimated. The US army was almost decimated twice over if you count total casualties (although they only lost about 5% dead). For most on his plate as far as area goes Nimitz or Mac probably qualify. Of course most of it was empty ocean. Come to think of it Yamamoto or someone else in the IJN command probably exceed either of the two American commanders in the Pacific.