At the start of 1862 the Confederate defensive line in the west ran along the Kentucky-Tennessee border (American Civil War). That line reached the Mississippi at Columbus. However, in February 1862 that line was broken when U.S. Grant captured Forts Henry and Donelson, key positions on that line. The Confederate commander in the west, General A.S. Johnston, was forced to fall back to a new line through Tennessee. Columbus was abandoned on 2 March. The new western end of that line, blocking the Mississippi River, was at New Madrid and Island No. 10.
As it crosses the Tennessee-Kentucky border, the Mississippi briefly doubles back on itself. Island No. 10 was at the start of this curve. New Madrid is downstream of Island No. 10, but because of the curve is actually further north than the island, on the northern (Missouri) side of the river. This meant that New Madrid was actually much more vulnerable to Union attack than Island No. 10.
Grant was not the only Union commander to be on the move early in 1862. General John Pope had been summoned to Saint Louis on 14 February, and given orders to capture New Madrid and Island No. 10. By 21 February Pope was at Commerce on the Missouri River, 30 miles north of New Madrid. The countryside between the two places was almost entirely underwater as a result of flooding in the flat river valleys. Pope had to advance along the line of a poorly maintained road, repairing it as he went. The Confederate defenders of New Madrid must have thought that the flooding made this route impractical, as they put up no resistance to Pope’s advance.
In theory the units that made up Pope’s army had a total strength of 26,000 men. Of those 22,808 were reported present for duty at the end of March. One confusing feature of the Civil War is that the two sides used different methods to count their armies. Of Pope’s 22,808, only 18,547 were actually ‘present for duty’ – the fighting men of the army. (compared to more recent armies this is actually a very high proportion of the army available for combat). A similar sized Confederate army would be reported as 18,500 strong, but would probably still contain a similar number of men.
Pope began the siege of New Madrid on 3 March. The town was defended by five regiments of infantry, 21 guns on land and another 40 or so on gunboats on the Mississippi. The high water levels meant that these gunboats would have been able to fire on Pope’s man during any assault. Island No. 10 prevented any Union gunboats from reaching New Madrid, so Pope was forced to sent north for heavy guns. While he waited for the arrival of those guns, Pope sent a small force to occupy Point Pleasant, twelve miles downriver from New Madrid, from where he in turn blocked the river to Confederate ships.
The Confederates were not idle. Feeling that Island No. 10 was safe, they transferred most of their men into New Madrid. By 12 March Pope reported that he was facing 9,000 men at New Madrid (7,000 would be later be captured at Island No. 10. That was the same day that his siege guns finally arrived. Overnight they were placed in position to bombard the town. On 13 March Pope opened his bombardment. The Confederate guns responded, and an artillery duel lasted for most of the day. Meanwhile, Pope’s infantry were slowly advancing their trenches in the normal pattern for a formal siege, slowly getting closer to the Confederate defensive lines.
That night the Confederate defenders of New Madrid abandoned the town and withdrew to Island No. 10. They had temporarily escaped from Pope, but were now trapped by the very features that made Island No. 10 such a strong position. Their only supply line was a narrow strip of dry line running south into Tennessee. However, Pope was now also stuck. While Island No. 10 stopped Union gunboats reaching him at New Madrid, he could not risk a river crossing. Nevertheless, Pope had captured a key Confederate position on the Mississippi, and with remarkably low losses. During the operations against New Madrid his army reported losses of 8 dead, 21 wounded and 3 missing, for a total of only 32 casualties.