The memorandum shows that Nelson originally contemplated a formation in three lines, an advanced division to windward, a main division under his personal command, and a lee division under his second-in-command, Collingwood. The final grouping of the ships in the battle was in two divisions. In the following list of the British fleet the names of ships are arranged in the same order in which they appear in Collingwood's dispatch, written after the action:—
| Windward Line. | |||
| Ships. | Guns. | Commanders. | |
| Victory | 100 | Vice-Admiral Lord Nelson. Captain Hardy. | |
| Téméraire | 098 | Cap"ain Harvey. | |
| Neptune | 098 | Cap"ain Fremantle. | |
| Leviathan | 074 | Cap"ain Bayntun. | |
| Conqueror | 074 | Cap"ain Pellew. | |
| Britannia | 100 | Rear-Admiral Lord Northesk. Captain Bullen. | |
| Agamemnon | 064 | Cap"ain Sir E. Berry. | |
| Ajax | 064 | Lieutenant Pilfold. | |
| Orion | 074 | Captain Codrington. | |
| Minotaur | 074 | Cap"ain Mansfield. | |
| Spartiate | 074 | Cap"ain Sir F. Laforey. | |
| Africa | 064 | Cap"ain Digby. | |
| Leeward Line. | |||
| Ships. | Guns. | Commanders. | |
| Royal Sovereign | 0100 | Vice-Admiral Collingwood. Captain Rotherham. | |
| Belleisle | 074 | Cap"ain Hargood. | |
| Mars | 074 | Cap"ain Duff. | |
| Tonnant | 080 | Cap"ain Tyler. | |
| Bellerophon | 074 | Cap"ain Cooke. | |
| Colossus | 074 | Cap"ain Morris. | |
| Achille | 074 | Cap"ain King. | |
| Dreadnought | 098 | Cap"ain Conn. | |
| Polyphemus | 064 | Cap"ain Redmill. | |
| Revenge | 074 | Cap"ain Moorsom. | |
| Swiftsure | 074 | Cap"ain Rutherford. | |
| Defiance | 074 | Cap"ain Durham. | |
| Thunderer | 074 | Lieutenant Stockham. | |
| Defence | 074 | Captain Hope. | |
| Prince | 098 | Cap"ain Grindall. | |
| Besides one frigate of 38 guns, three of 36, and two brigs of 12 and 8 guns. | |||
This was the fleet that lay off Cape Sta. Maria, some fifty miles from Cadiz, on Saturday, 19 October, 1805, and received from the frigates watching the port the message, passed on by connecting ships, that the enemy was at last coming out.
Villeneuve, like Nelson, had originally divided his fleet into three divisions. On the day of battle it fought in an order which was (as we shall see) partly the result of chance, arrayed in a long double line. He had deliberately mixed together in his array the French and Spanish units of his fleet, to avoid the dangers that might arise from mutual jealousies if they were drawn up in divisions apart. Instead of giving the list of his fleet according to the ordre de bataille drawn up in Cadiz harbour long before the event, it will be more convenient to arrange the list as they actually lay in line from van to rear on the day of battle.
The following, then, is the list of the allied Franco-Spanish fleet:
So far as mere figures can show it, the relative strength of the opposing fleets may be thus compared:—
| Line of Battle. | Lighter Ships. | |||||
| Ships. | Guns. | Frigates. | Guns. | Brigs and corvettes. | Guns. | |
| British fleet | 27 | 2148 | 4 | 146 | 2 | 20 |
| Allied fleet | 33 | 2626 | 5 | 200 | 2 | 30 |
But here once more—as so often happens in naval war—the mere reckoning up of ships and guns does not give the true measure of fighting power. The British fleet was immeasurably superior in real efficiency, and the French and Spanish leaders knew this perfectly well.