Mapping

"If we had a keen vision and feeling of all ordinary human life, it would be like hearing the grass grow and the squirrel's heart beat, and we should die of that roar which lies on the other side of silence. As it is, the quickest of us walk about well wadded with stupidity."

—George Eliot, Middlemarch

Long before Brooklyn became one of the most densely populated urban regions in the country, back when it was a modest hamlet on a bluff overlooking the prosperous harbor town of New York, a long ridge of thick woods ran through the center of the borough's current borders, stretching from present-day Greenwood Cemetery through Prospect Park all the way to Cypress Hill. Locals had given it a name straight out of Tolkien: the Heights of Gowan.

As geological formations go, the Heights of Gowan were hardly unusual. At their peak, they rose only two hundred feet over the glacier-flattened plains and tidal ponds of Long Island. Yet in the summer of 1776, the Heights found themselves at the center of world history. Just months before, the British had endured a humiliating retreat from Boston. Capturing New York, the trading center of the colonies and the gateway to the mighty Hudson (then called the North River), was the obvious countermove, given the British dominance in sea power.

Perched at the tip of an island facing a vast bay, New York presented an easy target for the king's armada. The problem lay in holding on to the city. From the fortified bluffs of modern-day Brooklyn Heights on Long Island, downtown New York could be continuously bombarded. "For should the enemy take hold New York while we hold on to Long Island, they will find it almost impossible to subsist," American general Charles Lee wrote. To hold on to the city without heavy casualties, British commander William Howe would ultimately need to capture Brooklyn. And Brooklyn was protected by the Heights of Gowan. It was not the topography that created the natural barricade but rather the dense canopy of eastern deciduous forest that covered the ridge, with its towering oaks and hickory trees and heavy thicket on the ground. An army could not hope to move a large mass of men and equipment through such an environment, and besides, if the battle turned into the forest, the Revolutionary forces would have the upper hand.

The Heights were not a perfect barricade, however. Four roads cut through the woods from south to north: Gowanus, Flatbush, Bedford, and a small gorge that went by the name Jamaica Pass. If the British chose not to make a direct assault on Brooklyn or Manhattan from the water, they would likely have to move their troops through these narrow conduits.

From the moment word spread in early June that the British ships had left Halifax, headed south, it was clear to everyone that the British would attempt to take New York. The question was how they would go about doing it. That was the crux of the decision that confronted George Washington in the long, quiet summer of 1776, as an imposing armada-the "four hundred ships in New York Harbor" that appear in the opening minutes of Hamilton-took anchor off the shores of Staten Island. Should he defend Manhattan or Brooklyn? Or, perhaps, should he concede that New York was beyond defending, a hopeless cause, and move the fight to more promising ground?

Washington was confronting a classic example of a full-spectrum decision, one that required him to think simultaneously on several different scales of experience. To make the right decision, Washington had to think about the topography of the land, those ridges and...