Ships sailing at night usually displayed lanterns from their sterns and masts, so as to avoid collisions and to allow groups of ships to maintain contact. Wishing to be as inconspicuous as possible, the French ships probably did not follow this practice. The French ships had all been issued with sealed orders, which they were to open on passing the Strait of Gibraltar; these instructed them that the fleet was to rendezvous at Cádiz. Knowing they had been observed by the British, La Clue changed his plan. Instead of heading for Cádiz, where he feared he could be easily blockaded by the British, he decided to sail more westerly, to clear Cape St. Vincent and head into the North Atlantic. However, the French navy did not have an effective system of night signalling. So at about midnight La Clue had his flagship, "Océan", light her stern lantern, turn to port (left, or westward) and reduce her speed. Normally, such actions would be accompanied by firing a cannon to draw attention. The naval historian Sam Willis suggests it is possible that La Cluewho had been ordered to avoid battle at all costsknowing the entire fleet was relatively close and not wishing to advertise his manoeuvre to the British, omitted to do this.