In the spring of 1864, General Ulysses S Grant began his "Overland Campaign", an ambitious attempt to end the war by destroying the Army of Northern Virginia, led by Robert E Lee, and take the Confederate capital of Richmond. By June, however, Union assaults and attempts to outmaneuver Lee's forces had failed, resulting in a stalemate. Grant decided on another ambitious plan: Union Army engineers would conduct one of the most consequential bridging operations in early modern military history.
In order to starve out the entrenched Confederate forces defending Richmond, Grant set his sights on the city of Petersburg, Virginia - 20 miles south of Richmond. Petersburg served as a vital commercial and transportation hub for the Confederate military. In order to achieve this, however, Grant would have to cross the James River - all the while masking his true intentions.
Fortunately, the Engineers of the Union Army were experienced. Since the beginning of the campaign, they had already built 38 separate pontoon bridges, with an aggregate length of 6,458 feet. Major Nathaniel Michler, acting chief engineer of the Army of the Potomac, later commented: “The facility, ease and promptness with which a thoroughly trained body of engineer troops can accomplish such important duties, also bear testimony to the zeal, energy, and ability displayed by both officers and men, and to the important services rendered by this arm of the service, not only during the weary marches of a long and trying campaign, but also in the preparation and execution of the more tedious [later] operations of the siege [of Petersburg].”
Grant tasked his men with finding suitable crossing sites - close enough to their target to push the initiative quickly while also maintaining just enough distance from Lee's forces to prevent a quick counterattack against his crossings. On June 12th, his officers returned with a recommendation: a location near Fort Powhatan that "was the narrowest point that could be found on the river below City Point.”
Grant had anticipated the need to cross the James River in force, and had made logistical preparations in April - he had sourced & staged bridging and engineering equipment at Fort Monroe. He ordered 155 pontoon boats (sometimes spelled 'ponton') and all associated men & material to the Bermuda Hundred settlement, while an additional battalion of bridge trains from the 50th New York went south.
Lieutenant Peter Michie was ordered to conduct an engineer reconnaissance in the vicinity of Fort Powhatan in order to determine suitable crossing sites. He focused on two - a potential ferrying location 3/4 of a mile upstream from Port Powhatan, and a bridge bridging site located at Weyanoke Point, 3 miles downstream. The width of the river at the latter point was approximately 1,992 feet. Major Michler, meanwhile, was ordered to occupy an entrenched bridgehead position at the crossing sites. General Lee and his officers, for their part, tried to ascertain the ultimate objective of any attempted crossing.
On June 12th, the Engineer Battalion moved out in full marching orders and crossed the Chickahominy River about 24 hours later, over the pontoon bridge built by the 50th New York. They soon made camp, ate, and rested while they awaited the passage of VI corps on the far side. The next few days would prove brutal as high temperatures ensured the Soldiers were miserable.
A mistake by unknown individual created an early headache - the bridging materials that had been sent to Bermuda Hundred in preparation had been inexplicably sent back to Fort Monroe, meaning it would take another 24 hours to reposition the equipment at Weyanoke point. This did not stop the Engineers, however, from getting preparations done. Led by their NCOs, 200 men jumped into the neck-deep muddy water and built an abutment of trestle work 150 feet long and reaching into the deep water - in just an hour.
General Benham, dispatched to retrieve the 15th New York and a number of vessels w/ bridge materials, arrived at noon on June 14th. He was soon followed by 200+ additional engineers of the 50th New York along with their bridge train. The bridge was built on both shores simultaneously, with successive "rafts" made up of 6 pontoon boats that had been rowed into position. Infantry troops, meanwhile, began ferrying across at their designated points.
Engineers had started building at 4:00PM on June 14th. They finished 7 hours later, with a total bridge length of approximately 2,170 feet, and using over 100 pontoon with 20 foot spans, center-to-center. It provided a roadway 11 feet wide between guardrails, and a draw 100 feet wide was incorporated so that vessels could still travel upstream and downstream as required. Three schooners provided anchorage.
Grant estimated that the combined strength of the Armies of the Potomac and the James was roughly 115,000 men. Over the course of 46 hours, the bridge was in near constant use - men, weapons, artillery, pack animals. It was noted that that the cattle herd (perhaps 3,000 head of cattle) & logistics trains stretched over 50 miles to the rear. The V Corps Chief of Artillery, Colonel Charles Wainwright, noted later: It was “really a wonderful piece of pontooning [sic], equal I suspect to anything of the sort ever done before. Very steady in crossing, nor has there been the slightest trouble as far as I can learn.”
While some subsequent tactical failures meant that Petersburg would not fall as quickly as hoped - a general officer failed to seize the initiative and press his early advantage - the crossings enabled Grant to funnel overwhelming numbers into the fight, forcing Lee to react quickly or lose his last supply lifeline. The Siege of Petersburg would, interestingly enough, be a dark sign of things to come in the First World War, as much of it was fought in trenches. It took 9 grueling months for the city to fall to Union troops.
Lee's Army of Northern Virginia was finally and decisively defeated during the Appomattox campaign, which followed the Siege of Petersburg. He formally surrendered on April 9th, 1865, at the Appomattox Courthouse. Jefferson Davis, president of the Confederate States of America, was captured soon after in May. Remaining Confederate forces would themselves surrender shortly after.
I hope you enjoyed this interesting piece of American military engineering history. Full credit goes to the author of the article I heavily referenced, Gustav Person, a retired Lieutenant Colonel of the New York National Guard. I highly recommend you read the whole article - I glossed over some details that are fascinating, simply for the sake of keeping this relatively short. You can find it here, where it also cites additional sources: apps.dtic.mil/sti/citations/
