I started reading this knowing a little of Portuguese history from several visits to the country. I found it a good account of the history through to 1807 - obviously written by a professional historian but very accessible and even quite gripping in an understated way.
Disney explains how portugal was born in the eleventh century - not from any cultural, linguistic or geographical separateness from the rest of the Iberian peninsula - but from wrangling for territory between Christian nobles as Muslim Hispania crumbled. The survival of this accidental county through to the twenty first century owes much to one spectacular stroke of good fortune: Portugal's golden age of discovery in the fifteenth century, and the opportunities that provided for ongoing colonial explotation, particularly of Brazil.
Given that the colonies became the major souce of political and economic power for this small marginal country, how to tell the story of Portugal, without getting irretreviably sidetracked into the history of Brazil, of Africa, of India? This author solves the problem by focusing only on the history of mainland Portugal for this first volume, focusing on the Portuguese Empire for the second volume. This works - Disney is able to maintain a narrative that otherwise would become far too confusing. But it leads to some strange effects as you read through the first volume: characters are prone to suddenly appear and disappear off the narrow Portuguese stage. It also means that the account of the Golden Age itself is somewhat muted.
Other than that, its a fascinating book, and I wish Mr Disney would write the rest of the story - from 1807 to the end of fascism in 1975 - an account of which doesn't seem to exist in English.