Final answer:
Gilbert shared the ambition of establishing an English colony in North America with his half-brother Sir Walter Raleigh, both seeking wealth from privateering against Spanish vessels.
Step-by-step explanation:
The sibling who tried to follow in William's footsteps is Gilbert. Gilbert shared a dream with his half-brother, Sir Walter Raleigh, of establishing a North American English colony. Sir Walter Raleigh was an adventurer like Gilbert and became one of the most famous courtiers of Queen Elizabeth I. Gilbert and Raleigh both were motivated by the wealth that could be gained from attacking Spanish galleons filled with gold, which brought riches both to themselves and to England. Their privateering activities also strategically maintained England's diplomatic neutrality, as they used their own ships rather than Crown ships for their expeditions.