This essay employs social network analysis to examine the means by which Admiral Horatio Nelson built up a wide range of contacts throughout his career and the ways in which he used the resulting social networks. Nelson's career provides ample evidence for such analysis, not least because the Royal Navy was the largest organisation of its day and a huge network in its own right. Not only did Nelson operate within and rely on this network, he was also one of its major actors whose activities were of major public, and now historical, importance. Moreover, sources which reveal his contacts to people both within and outside the navy are numerous and comparatively accessible.

Nelson's letters form the source base for this analysis. A number of subsequent printed collections supplement Nicolas's seven-volume edition of Nelson's correspondence published in the 1840s. These include three nineteenth-century editions containing Nelson's letters to Lady Hamilton; Naish's edition of Nelson's Letters to His Wife and Other Documents; several specialised editions covering particular aspects of his career; and the result of White's lengthy and intercontinental search for undiscovered letters. Each of these works added new material to the impressive 3,774 letters that Nicolas had managed to release into print. In total, 4,838 printed letters have been entered into a database that formed the basis for the analysis contained in this essay.

Nevertheless, this database, though thorough, is necessarily incomplete. During the early years of Nelson's career those to whom he wrote often did not feel any need for or interest in keeping his letters. This started to change gradually when Nelson was posted to the Mediterranean in 1794 and more dramatically when he became famous at the end of 1798, after the battle of the Nile. Even during the campaign leading to the battle of Trafalgar, however, not all of the letters Nelson wrote survived. This is evident from an examination of sources at the National Maritime Museum: a mere sample of forty letters to Nelson in the period 1803 to 1805 from the British ambassador at Madrid (John Holkham Frere), the British consul at Cadiz (James Duff) and the acting governor of Gibraltar (Thomas Trigge) indicates that quite a few of his letters are missing.