In the spirit of his famous saying, fifteen years later, "Were ten ships out of eleven taken, I would never call it well done if the eleventh escaped, if able to get at her," he determined to go with the troops.

With his temperament it was impossible to turn his back upon the little body of soldiers, whose toilsome advance up the tropical stream might be aided and hastened by his ready seamen.
The first objective of the expedition was Fort San Juan, a powerful work controlling the river of the same name, and thereby the only natural water transit between the sea and Lake Nicaragua.

Upon the possession of this, as a position of vantage and a safe depot for supplies and reinforcements, Dalling based his hopes of future advance, both west and south.

Nelson took with him forty-seven seamen and marines from his ship's company; the former, aided by some Indians, doing most of the labor of forcing the boats against the current, through shoal and tortuous channels, under his own constant supervision and encouragement.

A small outpost that withstood their progress was by him intrepidly stormed, sword in hand, by sudden assault; and upon reaching Fort San Juan he urgently recommended the same summary method to the officer commanding the troops.