Heroes

"...stone figures, representing heroes of an Empire dead so long its very existence was legend, stared down at them."
-Jerry Pournelle, King David's Spaceship (London, 1984), p. 198.

The Old Empire ended three hundred and sixteen years previously, long enough ago to generate some legends. We know from a list given in the following volume that those "heroes" are a mixed bunch:

Caesar
Ivan the Terrible (the first Tsar)
Napoleon
Churchill
Stalin
Washington
Jefferson
Trotsky

Even the fact that the First Empire was preceded by a CoDominium of the United States and the Soviet Union does not account for the inclusion of both Stalin and Trotsky on the same list.

Poul Anderson's Terran Empire, basing itself primarily on the Roman Empire, does not require such ideological obfuscation of past history. Its heroes might be:

Aeneas
Romulus
Caesar
Augustus
Virgil
Argos   

Battle On The Sand

Poul Anderson's Time Patrol series refers to seafarers, spacefarers and timefarers. In 976 BC, a battle at sea involves one contemporary ship and several far future timecycles. See here.

If space travelers colonize terrestroid planets, then those planets will have seas and seafarers. Anderson describes extrasolar battles at sea here and here.

Chapter Twelve of Jerry Pournelle's King David's Spaceship makes clear that its author understands sailing. Elsewhere, Pournelle tells us how he enlisted Poul Anderson as crew for his ocean racing sloop. (See Jerry Pournelle, "An Appreciation of Poul Anderson" IN Greg Bear and Gardner Dozois, Editors, Multiverse: Exploring Poul Anderson's Worlds (Burton MI, 2014), pp. 277-283 AT p. 280.)

Introducing superior sailing techniques to the backward planet, Makassar, the Samualites in their ship, Subao, outrun all but one of a pirate fleet. Makassar's two small close moons cause strong tides. Thus, when the tide races out of a shallow bay, Subao and her single remaining pursuer run aground and the two crews fight on the sand with swords, lances and crossbows. Subao has the advantage of two horsemen. When the tide returns in a single wave, one horseman gallops close enough to the pirates' ship to cut their anchor line so that their ship is cast onto the rocks.