He was Lord Lieutenant of Cornwall. Among other duties which the post entailed, was the important duty of keeping the county ready to ward off an invasion, which was a very real danger all through his period of office. His letters to Lord Burghley give ample evidence of his care and wisdom. In 1587, one year before the Armada, he sent the Lord Treasurer a letter in which he gave it as his opinion that a company of two thousand foot and a troop of two hundred should be levied from the counties of Cornwall and Devon, and should be trained to be ready for defence at a moment's notice against surprise. The difficulties of his plan he saw clearly. There was, in the first place, a feeling of rivalry between the two Duchies which increased the difficulty of combination. The Lord Lieutenant of Devonshire, the Earl of Bath, was not easily brought to see the wisdom of the plan, though Sir John Gilbert and Sir Richard Grenville, staunch Devon men, were its supporters. The merchants of Exeter were not disposed to bear willingly any additional outlay in the matter of defence, because they were obliged to pay heavily to defend their merchandise against Barbary and other pirates. Ralegh incloses a tabulated list in his letter, showing exactly how these levies could be raised, and the exact cost of the raising. The payment of the troop of horse is of much interest. The men were to receive 1_s._ a day (the pay of an infantry man was 8d.). The horsemen were to be divided into four cornets: that would imply four captains at 5s., four lieutenants at 3_s._, four guidons at 2_s._ 6_d._, four clerks at 1_s._ 6_d._, four trumpetts at 1_s._ 6_d._ per day. He adds the charge of ammunition. "There is allowed for each soldier for this service of sixteen daies, tenn pounde of Powder at 12_d._ the pounde and is £500. Ther is allowed of matche for each soldier at halfe a pounde the daye, at 6_d._ the pounde and is £200. Of leade for each mann one pounde at 1½_d._ the pounde, and is £6 8_s._ The whole estimated cost of training and raising came to £2163 5_s._ and unlike the majority of estimates, the one drawn up by Ralegh is as clear as it is concise.