Many thanks to you both, Howie and Steve - when the lead topic "Bad history" was followed by "Rory Muir's Salamanca" I was a little anxious!
But seriously, this sort of discussion is very useful. I've just been writing about the Vimeiro campaign (not a book, just a chapter, albeit a long one), and have been anxious over how many long quotes I can use, especially when describing the fighting. I suspect that the less expert the reader, the shorter they prefer the quotes, while those who have read a good deal on the subject rather like long(ish) quotes providing that they are from reasonably obscure sources and are lively. But I'd be interested in some feedback on this.