He returned to military service and was killed in 1864 during the Battle of Walkerton while leading a raid on the Confederate capital of Richmond, Virginia.

Union newspapers claimed the papers were forged and reports of mistreatment of Dahlgren's corpse inflamed public opinion in the North.

He visited his father who was meeting with President Abraham Lincoln and the U.S. Secretary of War Edwin M. Stanton at the time.

[8] After Ulric's summary of his experience, Stanton offered him a position in the U.S. Army as captain and aide-de-camp to General Franz Sigel.

[6] He was wounded in the foot on July 6, 1863, during the Battle of Gettysburg in a skirmish in Hagerstown, Maryland[10] and had his leg amputated below the knee.

Gen. Hugh Judson Kilpatrick on February 23, 1864, at a party and was invited to participate in an operation to attack Richmond, Virginia; rescue Union prisoners from Belle Isle and damage Confederate infrastructure.

[14] Dahlgren's forces were led to a ford on the James River near Dover Mills by an African-American guide, Martin Robinson.

They heard the sound of battle and rushed to support Kilpatrick but ran directly into a Confederate Home Guard force which halted their advance.

On the night of March 3, Dahlgren and a portion of his troops were ambushed near King and Queen Court House by 150 men in the 9th Virginia Cavalry under the command of Lieutenant James Pollard.

[16] The papers were orders to free Union prisoners from Belle Isle, supply them with flammable material and torch the city of Richmond.

The orders of Union troops purportedly were to capture and kill Confederate President Jefferson Davis and his cabinet.

[20] Union newspapers claimed the orders were a forgery and Dahlgren's father strongly denied his son would be involved in such a scandal.

He made four trips to Fort Monroe to try to arrange an agreement and even contacted the Confederate Commissioner of Exchange to formally request the return of Ulric's remains.