The forts of the eighteenth and nineteenth centuries were like snowflakes in their complexity and beautiful geometry. They were ephemeral too; they first appeared in Tudor times, with earthworks and bastions arranged in star or rose patterns, yet by the late nineteenth century they were all but redundant. This book will use The National Archives’ extensive collection of beautiful drawings and maps to explain the story of these structures- why they were built, their various functions and their immense historical legacy in laying the foundations of empire. Without forts, the history of America could have taken a very different course, pirates could have sailed the seas unchecked and Britain itself could have been successfully invaded.