Although victory at sea alone could not win the war, the British navy played a very significant role in the ultimate defeat of Napoleon, principally by achieving and retaining hegemony at sea. This allowed the relatively unfettered movement of troops and military supplies by sea, much faster than the French were able to achieve by land. It also ensured the security of the vitally important British maritime trade whilst restricting the trading capacity of Britain's enemies.

During the Revolutionary war and in the early years of the Napoleonic war the naval strength of Britain and its enemies was finely balanced. The British navy concentrated on destroying or neutralising enemy naval forces through successful fleet actions and relentless concentration on blockading their principal naval bases. Naval domination was almost complete after the decisive Battle of Trafalgar on 21 October 1805. In comparison, the weaknesses in the army had been regularly exposed during the period. Though there were successes in the West Indies they came at a high cost of life. All the European expeditions ended in failure. Indeed, until Lieutenant-General Sir Ralph Abercromby's campaign in Egypt in 1801 it was naval successes that sustained the morale of the British public and fuelled the political resolve to continue the war during this period.

Nelson's victory at the Nile did not remove the French from Egypt; neither did Copenhagen nor Trafalgar affect the French strategic position in Europe. Complete victory over Napoleon's forces would only be achieved on land and then only with the support of allies. If it was to be achieved, the army and the navy needed to engage in conjunct operations. These were most successful when inter-service rivalries were suppressed. However, there are numerous well-documented illustrations of tensions in army–navy relations. During the Revolutionary war, inter-service relations were particularly strained. In 1795 an infantry officer serving aboard a warship as a marine was dismissed from his ship by a naval court martial for insubordination to the captain and the army backed the officer.