Read War and Peace? An Infamous Army is War and Peace for the Regency romance set.
You have to read this the right way. Even though the book opens with familiar characters - Judith and Worth, Charles, Perry - you have to follow the narrative line with Wellington. Meaning you have to read it as a history narrative as opposed to a romance. There are huge gaps in the romance - just like there are gaps between the domestic storyline in War and Peace - to concentrate on preparations for the coming skirmish with the French (culminating at Waterloo) and extensive descriptions of the battlefield - also, just like in War and Peace. Although not QUITE as extensive in the battle sequences as War and Peace. There's only one - Waterloo - but it's pretty awful in the recounting of the staggering loss of life. Heyer gives Wellington excellent lines, many taken from his extensive correspondence. Thackeray's Vanity Fair also provides a slightly more contemporaneous look at English Society in Brussels in the run-up to Waterloo. Heyer's research for this book was extensive and very much respected.
On the romance side, Bab is a typical Alistair: provocative, daring, devil-may-care (she wears open-toe Grecian sandals with nail polish - le scandale!!). Charles is a bit in over his head with her behavior but he at least tries to take it all as part of her personality instead of being controlling. I think their story worked out very well. It was nice to see Judith and Worth interacting as a couple since in their book (Regency Buck) Worth was playing the creepy guardian angle whilst Judith was working at being a dandy (since there isn't really a feminine version of the word) and we didn't see them actually LIKE each other until the last half-chapter. Also reassuring to see that Dominic (now Duke of Avon) is still as nuts as he was in Devil's Cub while Mary is just as practical and good-hearted.