"mastery over the oceans"
British naval power
The Battle of Trafalgar by JMW Turner
reached its height with the Napoleonic wars and the victory at Trafalgar in 1805. For the next hundred years, Britain was unchallenged on the oceans: Britannia truly ruled the waves. British power was exercised abroad through “gunboat diplomacy”. With its total naval supremacy, the Royal Navy was able to counter piracy, enforce a ban on slavery, and chart the world’s oceans and coasts.