For it is followed by the battle order of a fleet in which both ships and captains correspond exactly with that which Dartmouth commanded in 1688.

The only other fleet which he commanded was that which in 1683 proceeded to the Straits to carry out the evacuation of Tangier, and it was not large enough to require such a set of instructions.
We know moreover that in this year he did actually draw up some Fighting Instructions, shortly after September 24, the day his commission was signed, and that he submitted them to King James for approval.

On October 14 Pepys, in the course of a long official letter to him from the admiralty, writes: 'His majesty, upon a very deliberate perusal of your two papers, one of the divisions of your fleet and the other touching your line of battle, does extremely approve the same, commanding me to tell you so.[1] Lord Dartmouth's articles follow those which James had last drawn up in 1673 almost word for word, and the only alterations of any importance all refer to the handling of the line in action.

There can be practically no doubt therefore that we here have the instructions which Pepys refers to, and that the new matter relating to the line of battle originated with Dartmouth, as the result of a considerable experience of naval warfare.

After leaving Cambridge he joined, at the age of 17, the ship of his cousin, Sir Edward Spragge, and served with him as a volunteer and lieutenant throughout the Second Dutch War.