It's good to be a river rat for a few days. Our family seat for the week, the 17th-century town of Snow Hill, Maryland, abuts the Pocomoke River, a middling-sized stream that meanders about seventy miles southward from Delaware through Maryland. The Pocomoke ultimately empties into the Chesapeake Bay, where its final stretch forms part of the Maryland-Virginia border. Spindly pine trees line its shores. Water lilies jut above the brown waters.
Like oceans and seas, rivers are thoroughfares for trade and commerce. They provide an outlet for diplomatic contacts and cultural interchange. And they can become theaters of conflict. Snow Hill owes its existence to its position at the farthest point inland that was navigable by 17th-century merchantmen and men-of-war. The Pocomoke was deep enough to accommodate wooden ships that drew up to 25 feet of water. Larger craft paused here to transfer their cargoes to shallower-draft vessels able to venture farther upriver. That, along with farming, was enough to make the town a going concern.
We often lose sight of the fact that riverine commerce, trade, and warmaking are a subset of sea power writ large. Before he became the toast of fin de siècle America with his treatise The Influence of Sea Power upon History, 1660-1783, Alfred Thayer Mahan compiled a nifty little volume on The Gulf and Inland Waters. In its pages Mahan calls attention not just to the oceanic geography of the Caribbean Sea and Gulf of Mexico — a theme to which he would return time and again — but to the internal waterways that offer access to the heartlands of North America.
Vouchsafes Mahan, rivers like the Mississippi constitute a blessing provided the nation can fend off outside aggressors. If not, they are a curse, allowing enemy fleets to strike deep inland and seize control of commerce — indeed, of national life, as his contemporary Sir Julian Corbett put it. That's why Mahan portrays the mouth of the Mississippi as the key strategic feature of the Gulf and Caribbean. Other sites — Key West, Mobile, my hometown of Pensacola — draw their value largely from their capacity to help defend the Delta.
American military history dramatizes the consequences when a power loses control of internal communications. In The Influence of Sea Power upon History, the sea-power evangelist depicts Union control of Confederate waterways this way: "Never did sea power play a greater or a more decisive part" than in the Civil War that determined whether the United States would remain one republic or split in twain. Southerners "admitted their enemies to their hearts" through their maritime fecklessness. By wresting away command of the Mississippi, the Tennessee, and other vital arteries, the U.S. Navy gained unfettered mobility around the Southern periphery while bringing waterborne communications to a virtual halt for the Confederacy. Economic life wilted.
Sea power, then, isn't just about battle on the high seas. History is replete with examples of riverine politics and warfare, from robber barons wringing tolls from traffic on the Rhine in the Middle Ages, to Western and Japanese gunboats plying the Yangtze during the imperial era, to U.S. operations along such waterways as the Mekong or the Shatt al-Arab in more recent times. Command of the high seas is one thing. Command of internal waters is a more intimate thing entirely