Following Jenkins' testimony and petitions from other West Indies merchants, the opposition in Parliament voted on 28 March 1738 to send "an Address" to the King, asking his Majesty to seek redress from Spain. More than one year later, all diplomatic means having been exhausted, on 10 July 1739 King George II authorised the Admiralty Board to seek maritime reprisals against Spain. On 20 July, Vice Admiral Edward Vernon and a fleet of warships departed Britain, bound for the West Indies, to attack Spanish ships and "possessions". War was not declared against Spain until Saturday, 23 October 1739 , one day after the attack on La Guaira, the principal port of the Province of Venezuela, which was controlled by the Royal Guipuzcoan Company of Caracas. After arriving at the island of Antigua in early October 1739, Vice Admiral Edward Vernon sent three ships under the command of Captain Thomas Waterhouse to intercept Spanish merchant ships that made the route between La Guaira and Porto Bello. Waterhouse spotted several small vessels in the port of La Guaira and decided to attack, implementing a rudimentary plan. The governor of the Province of Venezuela, Brigadier Don Gabriel de Zuloaga had prepared the port defences, and Spanish troops were well-commanded by Captain Don Francisco Saucedo. On 22 October, Waterhouse entered the port of La Guaira flying the Spanish flag. Expecting attack, the port gunners were not deceived by his ruse; they waited until the British squadron was within range and then simultaneously opened fire. After three hours of heavy shelling, Waterhouse ordered a withdrawal. The battered British squadron sailed to Jamaica to undertake emergency repairs. Trying later to explain his actions, Waterhouse argued that the capture of a few small Spanish vessels would not have justified the loss of his men.
Question: How many days after King George authorized the Admiralty Board to seek maritime reprisals against Spain did Vice Admiral Edward Vernon leave Britain for the West Indies?
Answer: 10