By April 1369 Ponthieu had fallen to the French, who followed up with a successful attack on Le Crotoy in early May. This led to fears of an attack on Calais, the possibility lending urgency to English preparations. On 7 May, Gaunt’s expedition was cancelled, and the men-at-arms gathered for his expedition were redirected to castles in the March of Calais. Manny, no doubt frustrated to find himself dictating strategy to Pembroke from Westminster, was also dispatched there. Nine king’s ships, including Galley Philippe and La Welifare, were manned and readied. Stones for the king’s catapults were requisitioned from Kentish quarries. Repairs were made to defences in Thanet and Kent which had fallen into disrepair during the 1360s and sheriffs and the clergy began arraying all men in the county between the ages of 16 and 60. Humphrey Bohun, Earl of Hereford, was made Captain of Calais with orders to hold the town until he was relieved. As ever, when a French invasion threatened, the projected response was to land a large English army in French territory to destroy the enemy shipping in harbour. This could also force the French to remove their army from Gascony, relieving the pressure on the prince.

By the time parliament opened on 6 June, the king had taken the decision to resume using the title king of France, another signal that war had begun. He was urged to this course by both houses. The Chancellor also addressed parliament about the French invasion fleet. The government had been aware of its existence since January, but French invasions had threatened many times previously without result. One source of concern on this occasion was an intercepted letter from the new king of Castile, Henry Trastamara, to Charles V, in which he pledged to support the French monarch by supplying two galleys for every one the French possessed. On 12 June, Gaunt was appointed Lord of Calais, Guines and Marck and prepared to cross the Channel with a large body of men-at-arms. On the same day the Admiralty of the North was revived. As Guy Brian was occupied at the other end of the Channel, a new admiral, Nicholas Tamworth, a tough Devonshire knight, former routier and retainer of Gaunt, was selected.