OK for narrative history but volumes III and IV are hard going because the story changes from great events in a few places to small events all over the place.

He tells a good anecdote about a Castellan in south-west France who let the French capture it by escalade while they were abed. He swore blind to the English authorities in Bordeaux that it was mere negligence. Sumption found his receipt to the French about the bribe they paid him....;O)