The Battle of Monocacy, also known as Monocacy Junction, occurred on July 9, 1864, near Frederick, Maryland, and was part of the Valley Campaigns of 1864 during the American Civil War. The battle was part of Early's raid through the Shenandoah Valley and into Maryland in an attempt to divert Union forces from their siege of Gen. Robert E. Lee's army at Petersburg, Virginia.^[61] Confederate forces led by Lt. Gen. Jubal A. Early defeated Union forces under Maj. Gen. Lew Wallace. This event marked the northernmost Confederate victory of the war. However, the engagement inadvertently provided a crucial delay in Early's march towards Washington, D.C., allowing Union reinforcements to bolster the capital's defenses. While the Confederates advanced to Washington and engaged in the Battle of Fort Stevens on July 12, they could not succeed and eventually retreated to Virginia.

During the Valley Campaigns, Union General-in-Chief Lt. Gen. Ulysses S. Grant sought to counter the Confederates in Virginia. Meanwhile, Lt. Gen. Early's forces had opened a route to the U.S. capital. Maj. Gen. Lew Wallace, in charge of the Union's Middle Department in Baltimore, aimed to protect a vital railroad bridge at Monocacy Junction, Maryland. On the day of the battle, Wallace’s objectives were to secure the road to Washington for as long as possible and to maintain a safe retreat line. Despite being outnumbered and eventually overwhelmed, Wallace's forces held off the Confederates long enough to achieve this strategic delay.

The aftermath of the battle saw the Union forces retreating to Baltimore and the Confederates proceeding towards Washington. However, the delay at Monocacy meant that by the time Early's troops reached the capital, Union reinforcements were in place to defend it. This rendered the Confederate efforts to capture Washington futile. Despite the tactical loss at Monocacy, the strategic delay was recognized as being of significant value to the Union cause. Reflecting on the events, Grant praised Wallace's efforts, emphasizing the larger benefit rendered by the delay despite the battle's defeat. While Wallace later proposed a monument in memory of the Union soldiers who died, his specific design was never built, though other memorials were erected in their honor.