The Knyphausen marker stands along the route taken by a British and German column on June 7, 1780. Lieutenant General Wilhelm von Knyphausen was a professional soldier from Hesse-Kassel who commanded German auxiliaries hired by Britain and at times directed the British garrison in New York. After the severe winter of 1779–1780 left Washington's army at Morristown hungry, unpaid, and weakened, British leaders believed New Jersey might be vulnerable to a rapid offensive.

Knyphausen assembled roughly five thousand British regulars, Hessian troops, and Loyalist provincials. They crossed from Staten Island to Elizabethtown Point and began marching inland toward Morristown, where destroying Continental camps and stores could cripple American operations. Morris Avenue follows part of that historic approach. The expedition also hoped local Loyalists might rally, but years of occupation, confiscation, and civil conflict had made public support uncertain and the countryside difficult to control.

New Jersey militia responded quickly, skirmishing from roadsides and delaying the column. Continental troops under Brigadier General William Maxwell and Colonel Elias Dayton joined the defense around Connecticut Farms, now Union. Bridges and constricted roads favored the Americans. Knyphausen's force advanced through sharp resistance, but its momentum slowed as defenders fell back toward stronger ground near the Watchung Mountains. The movement commemorated by the marker was therefore part of an active battle, not a ceremonial march.

The village suffered heavily. Buildings were burned, and Hannah Caldwell, wife of Presbyterian minister and Patriot chaplain James Caldwell, was killed in her home. Her death became a powerful American propaganda symbol, although whether the shooting was deliberate remains disputed. British and Hessian soldiers also died and were buried locally. The expedition failed to reach Morristown, and Knyphausen withdrew toward Elizabethtown after concluding that American resistance was stronger than expected.

A second attempt later that month culminated in the Battle of Springfield on June 23. Again British and German troops failed to break through the New Jersey defenses, and serious northern campaigning largely ended. The June operations showed that Washington's army, despite desperate conditions, could rely on layers of militia, regular troops, difficult terrain, and local warning networks. They also demonstrated the cost to civilians when armies used inhabited villages as avenues of advance.

The marker names the enemy commander and gives the scale and objective of his march, providing a useful counterpoint to memorials focused only on local Patriots. Knyphausen was neither a minor mercenary nor acting independently; he commanded a multinational force in a calculated British operation. The modern avenue obscures the uncertainty of that morning, but its alignment helps recover the campaign's geography. Following the road westward reveals how an invasion column was slowed, contested, and ultimately turned back before reaching Washington's base.