I read the autobiography of a general of the British Army a few years ago. General Richard Dannatt was commander-in-chief for a few years in the mid 00's. His account was of interest for me, because as a military man who grew up and rose through the ranks during the latter half of the 20th century, he got to experience the state of an armed force that was being continually reduced and undersupplied as the last remaining imperial commanders retired and the more pessimistic leaders took over.

There were photographs and written accounts of himself in Belfast as a platoon commander, through to his time as the "best job in any armed force", which was a colonel of his own loyal regiment, and finally as a member of the general staff who had to suffer the PR turmoil of the Gulf Wars and reforms which narrowed down to disarmament and masses of early retirements. It doesn't quite carry the sort of prestige as an account written by a 20th century American commander, and certainly not as exciting as the lives of British generals from centuries ago, but it showed me something of the state of contemporary military life.

As for your intention to learn about MacArthur. I know something of the man from a few books I have read about the Pacific theatre and the Korean War. The man was as mad as they come, and WWII had a lot of dangerously deluded commanders, such as Patton, Harris, Stalin, Tojo, Kai Shek... MacArthur takes the prize for it. The man was essentially a competent leader who mostly took the credit for his counterparts, yet who spent a long time building a cult of personality about himself, promoting only his lackies and complaining that as the senior commander, he should have had Eisenhower's job. He's an interesting character to read about, but it's alarming to learn what the man did to keep his position. Truman absolutely loathed the man, as well as many of his peers and fellow commanders.