Which one of the following events marked the end of the Civil War?

Stonewall Jackson's death at Chancellorsville

the cessation of fighting at New Orleans

Lincoln's assassination at the Ford Theatre

Lee's surrender at Appomattox Court House

The event that marked the end of the Civil War was Lee's surrender at Appomattox Court House.

Explanation:

The Battle of Appomattox was the last battle of the Appomattox Campaign for the Northern Virginia Army of Confederate General Robert E. Lee before he surrendered to Lieutenant-General Ulysses S. Grant. The signing of the surrender documents occurred in the living room of the house owned by Wilmer McLean on the afternoon of April 9th. On April 12, 1865, a formal ceremony marked the surrender of the Army of Northern Virginia, with the parole of its leaders and men, which in fact (as Lee's army was the largest of those left to the Confederation) ended the Civil War, although the fighting did not cease immediately on the whole American territory on the same date.

Lee's surrender at Appomattox Court House was the end of the Civil War

Lincoln died after the war ended, so that's wrong

The fighting continued regardless of Jackson's death

And fighting at New Orleans continued after the end of the war