The Pirates! In an Adventure with Napoleon is the fourth Pirates book and the second one I've read (I love The Pirates! In an Adventure with Scientists, the first book). Obviously I need to pick up the middle two books, because this one's just as awesome as the first one.
In this book, the Pirate Captain decides to give up pirating after a disastrous loss at the Pirate of the Year Awards. He and his crew end up on the island of St. Helena, where they're joined shortly afterwards by Napoleon. The Pirate Captain and Napoleon take an immediate dislike to each other.
I can't even begin to tell you how truly funny this book is. Many times I was laughing out loud, rather hysterically. I can't even think of the Pirate Captain's secret weapon to defeat Napoleon without starting to giggle inappropriately. These are funny books. I can't stress that enough. And since there's a great dearth of truly funny, witty books in the world (most supposedly funny books are just a collection of sad puns), I highly recommend The Pirates! books.