As a graduate student of English history, I love the Naval Records Society. This particular volume consists of a collection of documents relating to the Expedition to Lisbon in 1589, or The Counter Armada. This book was a cornerstone for my research. R.B. Wernham has a good introduction in the beginning, but the real fun lies within the letters, state orders, etc that come after. There are letters from Drake, the Queen, Sir John Norris, etc. As I said it is a compilation of documents that relate to the 1589 expedition (only English documents, you would have to go elsewhere for Spanish and Portuguese).