He was a world traveler who rarely left home, yet he plotted a course through history for Britain. George III, who reigned from 1760 to 1820, was a pathbreaking monarch and an armchair general whose thirst for knowledge led him to collect more than 55,000 maps, charts, prints and manuals to savor in his private library. To mark the bicentennial of his death, the Royal Collection Trust has digitized George’s colorful cache of military maps and documents, some of which date back to as early as the 1500s. Some represent rough sketches. Other items include highly polished engravings, vivid orders of battle and finely drawn landscapes that depict bygone theatres of peace and war.

The maps also reveal a tantalizing new portrait of the king, reflecting what he knew of the world beyond Windsor Castle, and the making of a very modern military mind. While the American Revolution marked a turning point for empire and colonies alike, it’s worth knowing that much of George’s life was marked by war. As Britain battled through decades of fighting with European and Asian powers, George heeded the history of each win or loss. His universes of interests—astronomy and art, science and culture—all collided in the private library that he built, book by book, behind the walls of Windsor. George’s love of precision, evident in the way he dated letters down to the minute, made him ideally suited to study military history.

The king was, as historian Rick Atkinson observed, “a demon for details.” Poring over his maps, George counted blankets for the British soldiers facing far-off troops. He tallied cannon in the French fleet and sized up foreign uniforms. He eyed the hasty fortifications of American militia. Anxiously, he peered back at the past for Dutch naval lessons. And as he walked the halls of present-day Buckingham Palace, George glanced over the custom-built mahogany stands that held maps like this Philadelphia print of Yorktown in 1781, “The Field where the British laid down their Arms.”

Here are a few of the maps that sparked George’s imagination. You can learn more about how history remembers America’s last king–in manuscripts, memories, medals, and coins–here.

1628, Siege of Havana

The king was a keen apprentice of military science from a young age. Carefully reconstructed scenes like this one by the Dutch engraver David van den Bremden, which shows the clash in the Caribbean between Spanish and Dutch fleets in the summer of 1628, gave George new ways to think about naval strategy. For an island nation, establishing maritime power was vital. Between 1660 and 1815, the British Navy vied for dominance at sea, faltering before the Dutch Navy’s prowess before finding success in a pivotal set of contests against the French. George nurtured the British Navy’s growth at home, mindful that distant battles could reshape the fate of empires.