France and Great Britain jointly acquired the cables between Calais and Dover, Boulogne and Folkestone, Dieppe and Beachy Head, Havre and Beachy Head, Piron, near Coutances, and Vieux Châteaux (St Heliers, Jersey).
He was a strong advocate of the groupflashing system as a means of differentiating lights, and invented an arrangement for carrying it into effect optically, his plan being first adopted for the catoptric light of the Royal Sovereign lightship, in the English Channel off Beachy Head.
On the 1st of July 1690 the allies were badly beaten at sea off Beachy Head, but on the same day William himself won a decisive victory over James's army at the Boyne in Ireland.
He became rear-admiral in 1690, and fought at the battle of Beachy Head.
A full account of the battle of' Beachy Head, written with ample quotation of documents, and for the purpose of vindicating Herbert, will be found in Admiral Colomb's Naval Warfare (London, 1 899).