It's taken moving to a non-English speaking country to realize how wide spread and common place the English languages is in the World. This has piqued my interest in learning about the origins of our bastard tongue and how it got to this position.
The book was first written in the 1980s and was most recently revised in 2002, which makes it sometimes sound out of date in style. I would also say that since then English has become even more dominant, and some cultures less resistant to it.
The first half of the book tells the tale(s) of how modern English evolved from a mixture of sources including Latin, French, German and Danish. The second half then follows the trail of a language spreading through a sometimes brutal colonial empire and then through Americas own 'empire', all along the way collecting new influences and evolving.
Full of wonderful insights, anecdotes and stories, highly recommended.