Next in line came Nelsons' flagship, Vanguard. As five of his force had already passed inside the French line, he now turned to engage Spartiate on the outside.
By ordering his attack on the French van and centre, Nelson had achieved one of the tactical aims of an 18th Century admiral, that of concentration. Although the French fleet was equal in number to his own, the ships in the French rear could not sail against the wind to support their compatriots in the van and so Nelson had achieved a local superiority of force.
By taking his flagship, Vanguard, to engage on the seaward side of the French line and with his remaining ships (Minotaur, Defence, Bellerophon and Majestic) following suit, Nelson now achieved another tactical aim and doubled the line. Even when fully manned no warship carried enough gun-crew to effectively man both broadsides simultaneously, so being engaged on both sides at once meant you were at a particular disadvantage.
In the gathering darkness, the ships of the French centre and rear could only wait for the action to come to them or for the light of morning to allow an attempt to escape from the confines of the bay.
Nelson's squadron could now systematically work along the anchored fleet, engaging each French ship in turn with overwhelming force.
The French were doomed.