Command of Revenge and death
Grenville was appointed Vice-Admiral of the Fleet under Thomas Howard. He was charged with maintaining a squadron at the Azores to await the return to Spain of the South American treasure fleets. He took command of Revenge, a galleon of new design that was faster and more maneuverable than older naval ships.
At Flores Island the English fleet was surprised by a much larger squadron sent by King Philip II of Spain. Howard retreated to safety, but Grenville faced the 53 enemy ships alone, leading his single ship in what amounted to a suicide mission, stating that he "utterly refused to turn from the enimie...he would rather chose to die than to dishonour himselfe". His crew was reduced by nearly 100 men due to sickness on shore, but he chose nonetheless to confront the far superior Spanish force. For twelve hours he and his crew fought off the Spanish, causing heavy damage to fifteen galleons. According to Raleigh's account, Grenville and his soldiers fought for hour after hour, "...until all the powder of The Revenge, to the last barrell, was now spent, all her pikes broken, fortie of her best men slain, and the most part of the rest hurt". The ship itself was "marvellous unsaverie, filled with bloud and bodies of deade and wounded men like a slaughter house".
The fight was later romanticised by the poet Alfred, Lord Tennyson in his work "The Revenge: A Ballad of the Fleet:" "Out-gunned, out-fought, and out-numbered fifty-three to one", Grenville was said to have wished to blow up his ship rather than give up the fight, as Tennyson wrote: "Sink me the ship, Master Gunner! – sink her! split her in twain! ... Fall into the hands of God, not into the hands of Spain!" Grenville's crew however refused to obey these suicidal orders and his officers surrendered what was left of their vessel to the Spanish, on a promise of fair treatment.
Grenville died of his wounds several days later, screaming that his men were "traitors and dogs", but the Spanish were not to enjoy their success, nor would Grenville's men survive their deliverance. The Spanish fleet was caught by a cyclone soon after and during a week-long storm Revenge and fifteen Spanish warships and merchant vessels were lost. Revenge sank with her mixed prize-crew of seventy Spaniards and English prisoners near the island of Terceira, at the approximate position 38°46′9″N 27°22′42″W.