The phrase "accepting command of" is correct and usable in written English.
It can be used in contexts where someone is taking control or leadership of a situation, organization, or group.
Example: "After much consideration, she decided to accept command of the project team to lead them towards success."
Alternatives: "taking charge of" or "assuming control of".
On accepting command of the American army, in 1775, he protested that he was unequal to the task and claimed that he had done everything in his power to avoid such a burden falling upon him.
But when the Civil War broke out, experienced naval officers were at a premium, and Preble answered his nation's call to duty, accepting command of the steam-gunboat Katahdin.
After Trenchard had walked home, he wrote to Weir accepting command of the as yet unformed Independent Air Force.
His reputation as a field commander established, Charles in 1792 reluctantly accepted command of the Prussian army against Revolutionary France.
Under the Second Republic he published many antisocialist pamphlets and accepted command of the Army of the Alps.
The previous November Ambrose Burnside had reluctantly accepted command of the Army of the Potomac after President Lincoln finally lost all patience with the combat-averse George B. McClellan.
You may find the occasional counterfactual sentence in a serious history book — What if Lee had accepted command of the Union army?
During the Civil War Higginson accepted command of the 1st South Carolina Volunteers, later the 33rd U.S. Colored Troops, the first black regiment in the U.S. armed forces.
Considered a traitor by some Italians, he at first supported King Ferdinand IV of Naples but later accepted command of the navy of the Parthenopean Republic, which was declared January 23 , 1799 when the French took over Naples.
In reforming the Italian army, Fanti opposed concessions to Garibaldi and his volunteers a position that made Fanti unpopular and led to his resignation in June 1861, but in April 1862 he accepted command of an army corps in Florence.
As a militant abolitionist, [Higginson] felt morally obliged to volunteer when the Civil War broke out, and in 1862 he accepted command of a regiment of runaway slaves stationed in South Carolina... [H]is optimism is cheering even at this late date.
