The French and Spanish fleet comprised thirty-three ships of the line, of which eighteen were French and fifteen Spanish; the British had only twenty-seven, but among these were seven three-deckers as against four on the side of the allies. It had the additional advantage of superior discipline and equipment, to say nothing of the genius of its commander. The British fleet advanced in two divisions, Nelson leading the weather division of twelve, and Collingwood the lee division of fifteen ships. According to Nelson's plan Collingwood was to attack the rear of the enemy's line, while he himself cut off and paralysed the centre and van. Both divisions advanced without regular formation, the ships bearing down with all the speed they could command and without waiting for laggards. Collingwood in the _Royal Sovereign_, steering E. by N., broke through the allies' line twelve ships from the rear, raking the _Santa Ana_, Alava's flagship, as he passed her stern, with a broadside which struck down 400 of her men. For some fifteen minutes the _Royal Sovereign_ was alone in action; then others of the division came up and successively penetrated the line of the allies, and engaging ship to ship completely disposed of the enemy's rear, their twelve rear ships being all taken or destroyed. Meanwhile, Nelson in the _Victory_, who had reserved to himself the more difficult task of containing twenty-one ships with twelve, held on his course, advancing so as to keep the allied van stationary and yet to prevent the centre from venturing to help the rear. He designed to pass through the end of the line in order to cut the enemy's van off from Cadiz, but, finding an opportunity, changed his course, passed down the line and attacked the centre. He passed through the line of the allied fleet, closely followed by four other ships of his division, and the five British ships concentrated their attacks on the _Bucentaure_, Villeneuve's flagship, the gigantic Spanish four-decker, the _Santísima Trinidad_, which was next ahead of her, and the _Redoutable_, which supported her. The centre of the allies was crushed and the van cut off from coming to the help of the rear, which was being destroyed by Collingwood.