Three weeks after taking command of the Union army on March 10, 1864, Lt. Gen. Ulysses S. Grant boarded a steamer in Northern Virginia and headed toward Fort Monroe for what he hoped would be a landmark step in winning the Civil War.

Arriving early on the morning of April 1, he patiently submitted to a 15-gun salute, then promptly went into a daylong meeting where he outlined the critical roles that Maj. Gen. Benjamin F. Butler and Rear Adm. Samuel P. Lee would play in a coordinated attack that might require sending forces from Hampton Roads into North Carolina.

Little did Grant know at the end of the day — when he and his officers settled in for a lavish dinner, cigars and brandy — that Butler would collar him the next morning and counter with a plan that was better.

So impressed was the new general-in-chief that he quickly agreed, setting in motion an epic expedition of 120 ships and 36,000 men that would steam far up the James from Yorktown, Gloucester Point and Fort Monroe and — for a few brief days in early May — come tantalizingly close to spelling the end of the Confederacy.

"It was a brilliant plan — and it should have ended the war," says Lee Hall Mansion historian J. Michael Moore, describing the victory that lay within Butler's grasp when he landed with an overwhelming force barely 15 miles from a surprised and poorly defended Richmond.

"But Butler was a militarily inexperienced general who was reluctant to take the initiative — and the West Point officers who had been sent to back him up just flat out failed him. So the Bermuda Hundred Campaign — which started out as a real threat to the survival of the South — just sputters and unravels into one of the greatest missed opportunities of the war."

A tempting target

Butler's expedition up the James wasn't the first time the head of the Department of Virginia had set his sights on the South's capital.

Early in February 1864, he'd worked closely with Col. Robert M. West — the Union commander at Williamsburg and Fort Magruder — and Brig. Gen. Isaac J. Wistar — chief of the powerful garrison at Yorktown — to launch an ambitious surprise attack across the Chickahominy River.

And even after the promising raid failed — due in part to the confessions of a Union deserter — he recognized the lightly defended south side of the city as a vulnerable target.

Former Peninsula Campaign corps commander Maj. Gen. Samuel P. Heintzelman saw the weakness, too, and he wrote from his post in Ohio to encourage and advise Butler just days after reading about the thwarted expedition.

That gave Butler a running start when he revealed the details of his plan, which not only held out the promise of much closer coordination with the Army of the Potomac north of Richmond but also preserved the concentration of Union forces that President Abraham Lincoln wanted near Washington, D.C.

"Butler was a detail freak — and he loved big complicated operations like this. He was very good at it," says historian Edward G. Longacre, author of "Army of Amateurs: Gen. Benjamin F. Butler and the Army of the James, 1863-65."

"So even Grant was impressed — and he gave Butler carte blanche to do what he wanted."

An army emerges

Working tirelessly over the following four weeks, Butler gathered nearly 16,000 troops of the XVIII Corps from across Hampton Roads, housing them in two vast tent cities outside the Union forts at Yorktown and Gloucester Point.

He drew another 18,000 men from the X Corps and the Department of the South, shipping them in from as far away as Florida.

As this new Army of the James assembled, his regiments drilled and dug in, making a show of erecting headquarters and support buildings designed for a long-term occupation.

But as far as the eye could see, the York was filling up with transports, barges and other craft needed to carry not only thousands of armed men but also horses, artillery, hospitals, pontoon bridges, ammunition and baggage wagons.

With Grant's help, Butler reached out to the Navy, too, conferring with Lee and Navy Secretary Gideon Welles in addition to meeting personally with Assistant Secretary Gustavus Fox at Fort Monroe.