From a military and maritime perspective:
* Circumnavigating the globe: This was a monumental achievement, the second successful circumnavigation after Magellan's expedition, and one that solidified England's position as a major seafaring power.
* Defeating the Spanish Armada: While Drake wasn't the sole commander in this victory, his role as a skilled admiral and his knowledge of Spanish tactics were crucial in the English victory. This established England's naval dominance in the Atlantic and changed the course of European history.
From a colonial and exploration perspective:
* His voyages of exploration and trade: Drake's voyages helped establish England's presence in the Americas and the Pacific, leading to the foundation of English colonies and trade routes. He discovered and claimed territories for the English crown, and his voyages contributed significantly to England's growing global influence.
Beyond tangible achievements:
* His reputation as a skilled navigator and bold adventurer: Drake was revered for his courage and his tactical brilliance. He was a symbol of English prowess and a popular figure in English culture.
Ultimately, it's difficult to pinpoint a single biggest achievement. Each of these accomplishments was significant and played a key role in shaping English history and Drake's legacy.