The fall of Island No. 10 was a significant blow to Confederate control of the Mississippi River (American Civil War). At the start of 1862 the Confederate defensive line in the west had run along the Kentucky-Tennessee border, reaching the Mississippi at Columbus. However, after the capture of Forts Henry and Donelson by U.S. Grant in February 1862 that line had to be abandoned in favour of one that that ran through Tennessee. The western end of that line was formed by New Madrid and Island No. 10. However, even these new positions were dangerously exposed to Union attack. At the end of February a force of over 20,000 men under General John Pope had been sent overland to capture the two strongholds. On 3 March he began a siege of New Madrid, on the northern bank of the river. On 13 March the Confederate defenders of the town pulled back to Island No. 10, abandoning the town.
Island No. 10 was the stronger of the two positions. The Mississippi twists and turns, wandering across the bottom of its valley. At Island No 10 it turns briefly north, to New Madrid, before turning south again, in a giant ‘S’ bend. Island No. 10, at the base of the ‘S’, was protected from overland assault by a combination of Reelfoot Lake and heavy flooding, which meant that the only possible approach to the place was from the south, along the east bank of the Mississippi. Pope’s problem was that he could not safely transfer his army across the river. A Union naval flotilla arrived in front of Island No. 10 on 15 March, two days after his capture of New Madrid, but the Confederate guns were too strong and too well sited for them to risk running past the guns, and so they settled down to bombard the Confederate position on the island.
This bombardment proved to be almost entirely ineffective. The strong current of the Mississippi made prolonged bombardment difficult, while the well-build defences of Island No. 10 protected the garrison so well that they apparently suffered no casualties at all during the bombardment.
Time was felt to be short. While the Union flotilla was stuck at Island No. 10 it was potentially vulnerable to Confederate counterattack. They were known to be building their own ironclads on the Mississippi River, including the C.S.S. Arkansas, then close to completion at Memphis. There was a real fear in April 1862 that those ships would appear at Island No. 10 and inflict serious damage on the Union gunboats.
The first attempt to solve this problem took advantage of the high water level and widespread flooding. A network of small streams, or bayou, spread out from the Mississippi along much of its length. At New Madrid St. John’s Bayou and Wilson’s Bayou run to within two miles of the Mississippi above Island No. 10. An old wagon road, now flooded, ran between Wilson’s Bayou and the river. Combined, these two features were almost a ready made canal. They just needed clearing out. This Pope’s engineers undertook to do in two weeks. The Confederates on Island No. 10 soon became aware of the work, but dismissed it as doomed to failure, although in the same report also noted that the position on Island No. 10 could only be held while the Mississippi remaining in flood.
The resulting ‘canal’ was very shallow. Fortunately, Mississippi paddleboats did not need much water. Pope had four stern wheel paddleboats, the biggest needing only 36 inches of water, as well as six coal barges, equally able to pass through the shallow water. However, he still wanted a proper gunboat below Island No. 10 to protect his troops as they crossed the river. Flag-officer Foote, the commander of the Union fleet, did not think it was possible for one of his ships to run past the Confederate guns, but Captain Walke, of the Carondelet, disagreed, arguing that with suitable preparation his ship could run past the guns on a suitably dark night.
Foote agreed to let him try. After several days of preparation, on the night of 4 April the Carondelet successfully ran the guns without suffering any losses. Early on 7 April a second gunboat, the Pittsburgh, also managed to get past the Confederate guns without lose. By now the canal had also been completed. Pope now had his gunboats and his transports.
He launched his attack on 7 April. The two gunboats bombarded the Confederate positions at Watson’s Landing, south of New Madrid, and west of Island No. 10. Pope’s troops landed soon after. Trapped by greatly superior forces, the Confederate defenders of Island No. 10 had no choice but to surrender. Exactly how many men were captured is hard to pin down. Pope claimed 7,000, while Confederate sources put the figure much lower, at around 2,000. With fifteen infantry regiments known to have been in the garrison, the Confederate number seems unbelievably low.
The capture of Island No. 10 was a key moment in opening of the Mississippi. Only one more position, Fort Pillow, remained between the Union fleets and Memphis. On the same day that Island No. 10 fell, U.S. Grant launched his counterattack at Shiloh, forcing General Beauregard to retreat back to Corinth and destroying any chances that Fort Pillow might be held. Two months after the loss of Island No. 10, the Confederates had been forced to withdraw from Fort Pillow, and had lost Memphis to the Union river fleet. The capture of New Madrid and Island No. 10 also had a dramatic effect on the career of General Pope. In the aftermath of a series of defeats in the Shenandoah Valley, Lincoln was looking for someone to command a new Army of Virginia. That command was given to Pope, one of a series of commanders summoned east after victories in the west. In his case that call ended in defeat, at the Second Battle of Bull Run.