Blackbeard first went to sea when he was quite young. to work for Pirate Hornigold. to fight the French. to sail to Spain.

The text states: "Teach began his career on the high seas at an early age when he sailed in the English Navy in the War of the Spanish Succession (1702-1713). After the war he joined the crew of the Pirate Hornigold." This indicates that he first went to sea at an early age and then joined Hornigold's crew.

Considering the options provided:

• The text states he began his career at an early age.
• The text states he joined the crew of Pirate Hornigold after the war.
• There is no mention of him going to sea specifically to fight the French or to sail to Spain as his initial reason for going to sea.

Therefore, the most accurate answer based on the text is that he went to sea when he was quite young, and subsequently worked for Pirate Hornigold.

Answer: when he was quite young.