April 6th and 7th saw one of the bloodiest battles of the war when Union General Grant attacked Confederate General Albert Sidney Johnston at Shiloh. Grant had utilized the Federal Navy to move his forces deep into Tennessee via the Tennessee River, camping at Pittsburg Landing. Rather than wait for Grant to attack, Confederate forces took the initiative and attacked the Federal camp, aiming to push the Yankees into Owl Creek Swamp to the west. But during the fighting, the Rebel lines became tangled and confused and the Yankees fell back to the northeast instead. The Federals made their stand at a sunken road, which became known as the Hornet’s Nest. General Johnston was killed that day and General Beauregard assume command of the Southern troops. During the night, Federal reinforcements arrived in the person of General Don Carlos Buell’s Army of the Ohio. On the morning of the 7th, the combined Union troops counterattacked, forcing the Confederates to retreat. The battle, the costliest in U.S. history up to that time, ended Confederate hopes that they could keep the Union out of Northern Mississippi Grant was vilified by the press for the loss of Union troops, and actually lost his command to General Henry Halleck for a time.
Also on April 7th, Union forces in south Missouri captured Island No. 10 in the vital Mississippi River downstream from New Madrid. More than 5,000 Rebels were taken prisoner.
April 8th saw Confederate survivors of Shiloh fall back to Corinth, Mississippi.
As part of the strategic plan to blockade southern ports, Union gunners began firing on Ft. Pulaski on April 10th. The fort, built in 1830 by, among others, a young Army engineer named Robert E. Lee, formed a barrier at the mouth of the Savannah River, protecting the port of Savannah. It was thought at the time that cannons alone could not reduce such a structure, but for the first time, the Union was using a Parrott Gun, a cannon with a rifled barrel that was more powerful and accurate than smooth bores. Over two days, the Union pounded the fort until the Confederate’s powder supply was threatened. The Rebel commander surrendered April 11th, making unnecessary what would have been a very bloody fight.
April 11th saw a close call for Union General Fitz-John Porter. The new observation balloon, invented by Thaddeus Lowe, was supposed to go up, but Lowe had become ill overnight and was unable to make the flight. Porter, instead, made the ascent. But the balloon’s tether snapped and the balloon with the General aboard began to drift towards the Confederate lines. A last-minute shift in the winds blew the balloon back into friendly territory.
April 12th began the episode that became known as The Great Locomotive Chase. 22 Union raiders led by James Andrews hatched a plot to steal a train and use it to destroy the tracks and tunnels of the Western and Atlantic Railroad, then the primary transportation for food and other war goods from the farms and foundries of Georgia. Andrews and his 22 men stole the train during a breakfast stop at Marietta, Georgia and headed north. Confederate troops and trainmen pursued, sometimes in a handcar for two days before the stolen locomotive broke down near the top of Ringgold Gap. The 22 raiders initially made good their escape, but were eventually captured. 14 were sent to Confederate prisons, but 8 escaped and the other 6 were eventually exchanged. Andrews and seven of his men were tried in Atlanta and hung, their bodies buried in unmarked graves.
April 12th was the day that the Confederates re-organized their army, combining the Army of the Potomac and the Army of the Peninsula into what would become the legendary juggernaut known as the Army of Northern Virginia.
April 14th was the setting of the stage for the Battle of New Orleans. On this day, Union Commodore David Farragut moved his fleet to the mouth of the Mississippi River. The next day, the fleet sailed up the river to Fort Jackson.
President Lincoln signed legislation freeing the estimated 3,500 slaves in Washington D.C.
April 16th saw the emergence of a fighting Union General, Winfield Scott Hancock. His forces attacked Rebel troops under John Magruder in an attempt to break the stagnant line at Yorktown.
Also on that day, the Confederate Congress passed a conscription act. This legislation proved highly unpopular in a country where the states were considered to be more powerful than the central government. This lack of national unity would eventually destroy the Confederacy.
On April 18th, the Federal fleet off New Orleans began a 5-day bombardment of Forts Jackson and St. Philip.
The Confederate house and senate debated the adoption of a flag designed by Robert Barnwell Rhett on April 19th.
The United States established the U.S. Mint in Denver Colorado on April 21st.
In the pre-dawn darkness of April 24th, the Federal fleet began slipping upriver. After about half the ships had snuck past Forts Jackson and St. Philip, the Confederates discovered them and opened fire. Most of the Federal ships successfully run the gauntlet. The ships dueled with a Confederate fleet at English Turn on the Mississippi, but arrived off New Orleans on the 25th, Farragut demanding the city’s surrender, which was partially afire.
On April 25th George Thomas, the “Rock of Chickamauga” was promoted to Major General.
After a month-long siege of Fort Macon, near Beaufort, NC, Union General John C. Parke began a heavy bombardment of the fort. Confederate Colonel Moses White, facing an impossible situation, surrendered the Fort on April 25th.
On April 28th, a major victory for the Union was achieved when the strategically vital city of New Orleans surrendered.
On April 29th, the Army of the Tennessee, under the command of Henry Halleck, began a glacier-like march on Corinth, Mississippi, covering 20 miles in 26 days.