Ralegh's imprisonment occurred when he was busily engaged in fitting out expeditions against the Spaniards to command the trade-route through the Azores. In 1591 a rough squadron had been despatched under Lord Howard; but the enemy had got wind of it, and had sent a powerful fleet to protect their vessels. Of this Lord Howard heard in time to avoid disaster; he weighed anchor from Flores where he was anchoring, and escaped. Sir Richard Grenville, however, refused to fly: with his small ship the _Revenge_ he awaited the attack, and the full fury of the Spanish Fleet fell upon him. His resistance was as gallant as his disobedience had been audacious. Ralegh wrote a superb account of his friend's undaunted valour, and his friend's death spurred him on to renewed enterprise against the Spaniards. In the following year, 1592, he took the chief part in an expedition which, under his management, was far more successful. "Sir Walter Ralegh," writes Hakluyt, "upon commission received from her Majesty for an expedition to be made to the West Indies, slacked not his uttermost diligence to make full provision of all things necessary, as both in his choice of good ships, and sufficient men to performe the action evidently appeared. For his shippes, which were in number 14 or 15, those two of her Majesties, the _Garland_ and the _Foresight_ were the chiefest; the rest either his owne or his good friends or adventurers in London." Sir John Burrough was in command, and under him was the stern Sir Martin Frobisher, whose rigour even the hardiest sailors disliked. Contrary winds prevented the fleet from sailing for some weeks from the western ports where they were anchored; and the Queen, disliking the delay, recalled Ralegh. But Ralegh, being deeply involved in the enterprise, did not obey her first summons. The wind at length became favourable; and he set sail. But when they were, on May 11th, off Cape Finisterre, "a tempest of strange and uncouth violence" arose, and Sir Walter himself in the _Garland_ was in danger of being swallowed up by the sea. The storm did much damage to the vessels. Moreover, they had learned from two ships homeward bound for London, that no Spanish vessel would move that year, and that the hope of plunder in the West Indies was small. Accordingly, Ralegh determined to divide his fleet into two squadrons, one under the command of Sir John Burrough, and one under the command of Sir Martin Frobisher, and to lie in wait, the first at the Azores, the second by the Spanish coast "to amuse the home fleet." He himself then returned home, and forthwith on his arrival was imprisoned in the Tower of London.