His first experience of naval warfare was as a volunteer and lieutenant under his cousin, Sir Edward Spragge, in 1665.

Spragge was in fact his 'sea-daddy,' and with one exception all the examples in the 'Observations' are taken from incidents and movements in which Spragge was the chief actor.

One long observation is directed to precautions to be taken by flag officers in shifting their flags in action, so as to prevent a recurrence of the catastrophe which cost Spragge his life.

Indeed, with the exception of Jordan, Spragge is the only English admiral mentioned.

Dartmouth was present at all the actions quoted, and succeeded in constituting himself a sufficient authority on naval affairs to be appointed in 1683 to command the first important fleet that was sent out after the termination of the war.