Antony Beevor is indeed a first class historian but beware, not all his books are equally enjoyable.
"Stalingrad: The Fateful Siege: 1942-1943" is quite superb and recommended to all, plus "The Fall of Berlin 1945" which is also very good.
However... the one I wanted to be excellent, wasn't: "The Battle for Spain: The Spanish Civil War 1936-1939" which was his first book and simply over crammed with names, dates, events, flicking backwards and forwards in time and from region to region without holding the narrative together. It is the only book I have started but never finished - it was his first book and he hadn't learned his trade which is a shame because I hoped he'd be able to guide me through the Spanish civil war as painlessly as possible.
Otherwise, a superb author.