For me this was a first-hand description of the city as it was bombed and shelled with mortars, and burned and ransacked by looters. She named the shops that were closed and boarded up, the hotels and bars that no longer had anything to offer but black coffee. She pointed out that some people were using the chaos to settle grudges and some seemed to have gone quite mad. Her pen portraits of the other ex-pats were also very enlightening and while she obviously had a great deal of sympathy for the Spanish, it wasn't shared by everyone.
Anecdotes such as this were not something I could have made up. You needed to be there at the time to see what it was like.
Koestler also gave a first-hand account of walking along the road to Álmeria while the fleeing refugees were bombarded by the gunboats. He refers to it as 'sheer target practice' and describes how he and his companion threw themselves on the ground, trying to make themselves 'as flat as flounders'.