The Battle of Brooklyn was fought not only across the hills, woods, and fields of our end of Long Island, but also on the waters surrounding New York Harbor.  The waterways, were in fact, key to the whole American Revolution.  The ship Red Hook repelled was the new frigate HMS Roebuck, a new prototype the British designed specifically to fight in the shallow waters of the American coast and rivers.  The British had generally specialized in naval warfare in deeper ocean waters.

The importance of the waterways to the American Revolution is explained near the start of Episode 3 (about the Battle of Brooklyn) of the Ken Burns' documentary "The American Revolution."

Rick Atkinson says, “ New York is an archipelago, it's a confluence of Islands. It's a problem if you don't control the naval approaches in and around New York, you cannot properly defend New York. 

The narrator says, “New York was one of the best natural harbors on the Atlantic seaboard, and although the town still occupied just a single square mile at Manhattan’s  southern tip, it was the second largest city in the newly created United States and the gateway to the Hudson River.  If the British commander Gen. William Howe, could capture it, his forces would be free to ascend the river and divide rebellious, New England from the rest of the states.”

Nathaniel Philbrick says, “This whole war in many ways is a water campaign. It's who controls the coast, but it's also who controls the rivers and the lakes. This is where the fighting would be, wherever water provided you with a way to get into the interior of the country.” 

Admiral Richard Howe's powerful fleet worked in close cooperation with General William Howe's army, controlling New York Harbor, transporting thousands of soldiers between Staten Island, Long Island, and Manhattan, and threatening to cut off any avenue of escape for the Continental Army.

More than 400 British and transport vessels supported the invasion, while numerous warships, including frigates, ships-of-the-line, and smaller armed vessels, patrolled the harbor's channels and rivers.

One of the most important waterways was the narrow Buttermilk Channel, separating Red Hook from Governors Island. If British warships could force this passage and enter the East River, they could position themselves between Brooklyn and Manhattan, trapping General George Washington's army against the harbor. Guarding this critical approach was Fort Defiance, an American shore battery constructed over high bluff of a Red Hook island which no longer exists Cypress Tree Island. Armed with heavy cannon commanding the channel, the fort was designed specifically to deny enemy ships access to the East River.

On August 27, 1776—the same day the Battle of Brooklyn raged inland—the new 44-gun British frigate HMS Roebuck attempted to test the American defenses and force her way through the Buttermilk Channel.

Other British vessels were present in New York Harbor, supporting the campaign and standing ready to exploit any breakthrough, but the Roebuck became the principal ship engaged in this particular action.

Unfavorable winds, pushed her close to Fort Defiance as she advanced. Both ship and fort opened fire at such close range that the fighters could hear the men of the opposing side. The exchange quickly developed into a sharp artillery duel. American shot struck the Roebuck several times, damaging her hull and rigging and making further progress through the confined channel increasingly hazardous.

The weather worsened, and faced with accurate fire, difficult navigation, and the risk of becoming stranded or exposed in the narrow waters, the Roebuck withdrew from the immediate engagement.

Rather than abandoning the operation altogether, she retired temporarily to safer waters, where repairs could be made and conditions reassessed. The British Navy remained in control of New York Harbor, but the attempt to force the East River through the Buttermilk Channel had been delayed.

Two days later, following the crushing American defeat around what's now Prospect Park and the Old Stone House of Gowanus, Washington found his army in an increasingly desperate position. Over  9,000 Continental soldiers occupied defensive lines around Brooklyn Heights, while British forces surrounded them on three sides. The East River offered the only route of escape; but if British warships entered the river in force, the Continental Army could be trapped and forced to surrender—an outcome that might have ended the Revolution before it had truly begun.

On the evening of August 29, 1776, Washington ordered one of the most remarkable military withdrawals in history. Colonel John Glover's skilled Marblehead mariners from Massachusetts quietly ferried soldiers, horses, artillery, wagons, and supplies across the East River to Manhattan using a fleet of small boats.

And there were other challenges.  According to the 2021 book “The Indispensables” Chapter 30 “American Dunkirk,” by military historian Patrick K. O’Donnell, there was a lot of concern about spies since Brooklyn Heights had many Tory residents allied with the British.

The techniques used to address this concern were:  the Marbleheaders muffled the sound of their oars by wrapping the blades in fabric; no departing troops were told in advance where they were going, all men were ordered to not speak or even cough.

Nonetheless, the avid Loyalist Catrina Rapalje, as legend goes, found out and instructed an enslaved Black servant to report the evacuation to the British. He spoke Dutch and only broken English but the troops he first encountered were Hessians who didn’t speak English. It was hours before the Hessians brought him to English speakers. Catrina’s message did not get through in time.

The Marbleheaders had tides and winds in their favor and then not, and then back again. A peculiar fog settled in around 2am, muffling noise and impeding visibility. Over the night, more than 9,000 troops, horse, cattle, and cannon escaped. By dawn on August 30, the last Continental troops had crossed safely to Manhattan, leaving the British astonished to find the American lines abandoned.

The successful retreat resulted from a combination of careful planning, disciplined execution, favorable weather, tidal conditions, and British caution.

General Howe chose not to launch an immediate assault against the American fortifications after his victory, preferring instead to prepare for a formal siege. Meanwhile, the earlier resistance at Fort Defiance had demonstrated that the Buttermilk Channel was not easily forced and contributed to delaying British naval movement into the East River during a critical period.

Historians generally view the weather, tides, Washington's leadership, and British decisions as the primary reasons for the successful evacuation, the determined stand by Fort Defiance formed one part of the larger chain of events that helped preserve the Continental Army – as well as Catrina Rapelje’s enslaved servant not finding English speakers fast enough.

The engagement between HMS Roebuck and Fort Defiance is an example of how the campaign for New York was fought as much on the water as on land. Control of the harbor's narrow channels was vital to both armies, and even a temporary delay imposed on the world's most powerful navy could have strategic consequences. By denying immediate passage through the Buttermilk Channel, Fort Defiance helped complicate British naval operations at a moment when every hour mattered, allowing Washington's army the opportunity to escape and continue the struggle for American independence.

Footnote: Despite Catrina and her wealthy husband John Rapalje being traitors to the American cause, the name of Rapalje family lives on, with anglicized spelling, in the short Rapelye Street between Red Hook and Carroll Gardens.

The Repelje family was one of the first Dutch families to arrive in New Amsterdam, and a Rapelje was the first colonist baby born in what’s now New York State. It’s surprising that their name is on a Brooklyn street; because Catrina and John were vocally loyal to the King of England, and “drank tea in defiance of the revolutionaries” as O’Donnell puts it. He reports that “In October 1779, the New York Act of Attainder declared that John Rapelje and fifty-eight other people were “Ipso Facto, convicted and attained” of being enemies of the state. It further reported that the state had the right to seize their property and execute Rapalje and the others named in the act. Rapalje fled to England, taking with him the town records, much to the chagrin of Brooklyn residents. He lived in England until his death.”

Lines of a Roebuck-class ship, one of a set of plans in the Collection of the Royal Museum, Greenich