William the Conqueror (William I) is most famous for leading the Norman Conquest of England in 1066. As the Duke of Normandy, he crossed the English Channel and defeated King Harold II at the Battle of Hastings, fundamentally altering the course of English history. This high-fidelity victory ended Anglo-Saxon rule and introduced a new Norman-French aristocracy, which significantly influenced the English language, law, and architecture. William is also renowned for commissioning the Domesday Book in 1086, a high-fidelity "Great Survey" of much of England and parts of Wales, which remains one of the most important historical documents in the world for its detailed record of land ownership and resources. His high-fidelity physical legacy includes the construction of the White Tower at the Tower of London, which he built to assert his power over the city. To this day, the "High-Fidelity" lineage of the British Monarchy can be traced directly back to William, making him the foundational figure of the modern English state.