Siege of Yorktown, 4 April to 4 May 1862

Battle during the American Civil War that first suggested that all was not well with General George McClellan’s Peninsula Campaign. A force of no more than 11,000 men, spread out across the Peninsula east of Richmond, stopped the advance of over 50,000 Union solders on 4 April, and delayed the progress of that army for a month before withdrawing just before McClellan was finally ready to begin bombarding the Confederate lines.

Having taken command of the Army of the Potomac after the disaster of First Bull Run (21 July 1861), McClellan had undoubtedly created a very fine army. However, over the autumn and winter of 1861-2 he had done nothing with that army. Worse, he had refused to give any information about his plans for 1862. As the winter dragged on, McClellan’s inactivity and silence caused a rising tide of criticism in Washington. Worse, he was a known democrat, and so to some his motives were suspect.

Finally, on 27 January 1862 Lincoln issued his General War Order No. 1, in which he ordered all Union armies to begin a general advance on 22 February (George Washington’s birthday). Four days later, on 31 January 1862 he issued Special War Order No. 1, in which he ordered the Army of the Potomac to advance on the line from Washington, through Manassas Junction and on towards Richmond.

The main purpose of this order appears to have been to force McClellan to reveal his own plan. It worked. On 3 February McClellan wrote a long letter in which he gave the details of his plan. He wanted to use the Union’s control of the sea to move the army down to coast to Urbana, on the Rappahannock River. If Johnston’s army remained around Centreville, it would find itself twice as far from Richmond as McClellan. In theory this would allow McClellan to march into Richmond almost unopposed (in reality, McClellan never seemed to master rapid movement – one can’t help but feel that Johnston would have been given plenty of time to rush back to Richmond!).

In the event, Johnston pre-empted McClellan’s plan. His army was at best only a quarter as large as McClellan feared, and its position at Centreville was obviously vulnerable to being outflanked by sea. Johnston’s main fear at the start of 1862 was that McClellan would march down the Maryland shore of the Potomac, cross over near the mouth of the river and cut him off. Accordingly, on 9 March 1862, the Confederate army left its positions around Centreville.

McClellan was still at Washington. As Johnston withdrew, he did actually move across the Potomac in force (and relatively quickly), but only in the hope of catching the Confederate rearguard. As the Union soldiers entered the Confederate lines, it became clear that the Confederate position had never been as strong as believed, nor had their army been as large as expected.

The Confederate move also forced McClellan to adopt his fallback plan, for an attack via the peninsula between the York and James Rivers, starting from Fort Monroe, a Union held position at the tip of the position. With much of the strategic purpose of the move gone, McClellan now emphasised other advantages, including the apparently superior quality of the roads on the Peninsula, which would allow his army to move much more quickly than the muddy tracks in north Virginia.

The army began to move during March. Two of the four corps were to move to Fort Monroe at the tip of the Peninsula and march along it’s full length. Another was to move further west, to outflank any positions on the Peninsula while McDowell’s corps was to move to West Point, at the north western corner of the Peninsula. McDowell’s corps never made that move. McClellan had to fight at Yorktown with the two corps landed at Fort Monroe, although this still left him with many many more men than Magruder.

McClellan’s initial plans were based on poor intelligence. His assumption was that the Confederates would fortify Yorktown just as the British had done during the War of Independence, allowing McClellan to bypass it to the south and isolate the garrison. This theory was based in part on a poor quality map of the Peninsula that placed the Warwick River parallel to the York and James Rivers, running along the length of the Peninsula. Instead, it flows almost completely across the Peninsula from north to south, presenting a potentially formidable barrier to any army.

The Confederate commander, General John Magruder, had taken advantage of the line of the Warwick to construct a fortified line across the entire peninsula. His fortifications at Yorktown were thus only the northern end of his line. McClellan would have to fight his way through. However, when the two armies first came into contact, Magruder had at most 17,000 men, to face a Federal force of at least 42,000 men (probably many more, perhaps as many as 60,000, but the exact figures for effective troops present at Fort Monroe at the start of April are not clear – a situation not helped by McClellan’s tendency to exaggerate the size of units removed from his control while underestimating those that he had retained!).

McClellan arrived at Fort Monroe on 2 April. Parts of his army had been present in force at the tip of the Peninsula for some time, but had not used the time to reconnoitre the Confederate positions in any detail. Thus, when the army began to move on 4 April McClellan still had no clear idea of the Confederate positions.

As the great march finally began, McClellan’s promise of better weather and good ‘sandy roads’ was proved to be no more than wishful thinking. Heavy rains began, and the roads on the Peninsula soon turned out to be no better than those in Northern Virginia that McClellan had put so much effort into avoiding! McClellan’s reports were filled with complaints about the roads for the rest of the campaign!

Worse was to come. As the army moved west, the left flank was expecting an easy march past Yorktown. Instead, as they advanced through the rain a line of Confederate defences loomed before them. Magruder had fortified the entire line of the Warwick River, giving the Confederates a thin grey line across the Peninsula.

It was a very thin line. On 5 April Magruder had 12,000 men, of whom half were in the fixed defences around Yorktown. The remaining 6,000 men were spread out along thirteen miles of defences along the Warwick River, at rather less than 500 men per mile. At worst, McClellan could have attacked this line with some 25,000 men. Magruder certainly expected an immediate attack, and ordered his men to sleep in the trenches.

To his relief, McClellan stopped. In his report on the Peninsula campaign, McClellan described the line on the Warwick as virtually impregnable. His corps commanders appear to have shared his view. At the southern end of the Confederate lines one crossing point over the river (Lee’s Mill) was defended by what even McClellan called the ‘One gun battery’ (correctly), and yet was still considered to be too strong to assault!

Magruder not had much time to prepare his line along the Warwick. His first plan had been to hold the Union advance even further east, but lack of men forced him to pull back to what he felt was a weaker line but one that could possibly be held for a period with the troops under his command. The fortifications around Yorktown required half of his men. Along the line of the Warwick River, Magruder used a series of five dams to raise the level of the river, making it almost impassable for most of its length. Two of these dams were associated with mills (Lee’s and Wynn’s) while the final three had been built by the Confederates. Each of the dams was protected by artillery and extensive earthworks, in order to prevent McClellan’s men destroying them.

McClellan’s chance to easily break the Confederate line soon passed. The Confederates proved able to quickly reinforce Magruder from troops in the immediate vicinity and from the main Confederate army, recently withdrawn from Manassas. By the time Magruder was superseded, he was confident that his defences could withstand any possible assault.

No such assault came. On 16 April the Federals launched an attack on the position at Lee’s Mills, partly to find out exactly what the Confederate position actually was (it was largely hidden in the trees that lined the Warwick), and partly to see if the Confederates could be forced out of their positions by an artillery bombardment. At the time Magruder felt that this attack was intended to be a serious attack on his lines, partly because McClellan was seen to be watching the fight develop. Ironically, McClellan’s presence removed any chance that a serious assault might have developed.

Instead of risking an assault, McClellan now prepared for a formal siege. For the rest of April his men worked to put their siege guns in place ready to bombard the Confederate lines. Finally, by the start of May he was about ready to open fire. By now, McClellan had convinced himself that he was outnumbered along the Warwick, and had already begun his endless stream of calls for reinforcements. After a winter of delays and inaction around Washington, this renewed inactivity on the Peninsula began to worry many in Washington, and provoked some increasingly pointed messages from President Lincoln.

All was not well on the Confederate side. From Richmond the situation looked much worse. An increasingly large Union army was now established threateningly close to the Confederate Capital. Joseph Johnston, the Confederate military commander in Virginia had a rocky relationship with President Jefferson Davis. Robert E. Lee was now in Richmond, acting as the President’s military advisor.

They now clashed on the issue of when to withdraw from the Yorktown line. On 22 April Johnston reported that the Yorktown lines were so weak that ‘only McClellan could have hesitated to attack’. He recommended an immediate withdrawal to defensive positions around Richmond, but was overruled by Lee. It was only at the start of May, when it was clear that the bombardment was about to begin, that Johnston withdrew from the Yorktown lines. On the night of 3-4 May, the Confederate troops withdrew with such skill that it took the Union forces some time the next day to realise they were gone!

The siege of Yorktown took most of the point out of McClellan’s Peninsula campaign. The loss of a month allowed the Confederates to prepare new positions around Richmond and to move reinforcements to oppose the Federal advance. However, despite the month lost at Yorktown, McClellan was still in a very strong position. He would soon be in place to attack Richmond, with, if he had only known, a much larger army than could be found to oppose him. The successful defence of Yorktown was just the first of a series of Confederate successes to which General McClellan was to make important, if unintentional, contributions.

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How to cite this article: Rickard, J (29 June 2006), Siege of Yorktown, 4 April to 4 May 1862,

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