One decisive reason the Federals won the war on the rivers was the rapid creation and utilization of gunboats. These vessels protected transports, patrolled the rivers, shelled Confederate defenses, directly supported Union amphibious operations, and more than once saved a Federal force from destruction by pouring fire on victorious Confederates. Dramatic examples include Milliken’s Bend in June 1863 and Baton Rouge in August 1862, where Union garrisons were saved from annihilation. Ulysses S. Grant escaped at the Battle of Belmont in September 1861 under the guns of timberclads USS Tyler and USS Lexington.
Perhaps the most famous example of gunboats aiding the army in a battle was at Shiloh. The Union army also had the support of Tyler and Lexington, the only navy ships around since ironclad USS Cairo and timberclad USS Conestoga had been called away. Both were commanded by Lieutenant William Gwin, a young officer who in time would have several warships named after him due to his exploits. The Tyler was originally named A.O. Tyler, but some called it Taylor so as not to associate the vessel with John Tyler, the former president who served in the Confederate Congress. The timberclads were second-line warships. Although well armed, they were vulnerable to heavy cannon, and as such usually supported the ironclads.
On April 6, Gen. Albert Sidney Johnston’s Army of the Mississippi surprised Maj. Gen. Ulysses S. Grant’s Army of West Tennessee. Fighting was bitter and fierce from the first volley. By noon, the carnage had already surpassed Bull Run and Fort Donelson, and by 2:30 p.m. Johnston was dead. The Confederates, despite some bungled attacks, gradually forced the Federals towards the banks of the Tennessee River. As they did so they came in range of Gwin’s gunboats, which waited for orders but received none from Grant. Eventually, Gwin managed to get directions from Brig. Gen. Stephen Hurlbut. At 2:50 p.m., Gwin opened on the Rebel right. The shots often went wide and entered Duncan Field. Losses were light among the Confederates, but many noted the loud booming of the cannon. Still, at this point Gwin’s timberclads had no real effect on the battle.
The gunboats were more important as the Confederates arrayed for the final push across the ravine that straddled Dill Branch. Hurlbut directed them to fire into the area of Cloud Field, the bombardment beginning at 5:35. Maj. Gen. Braxton Bragg, who was organizing the attack at Dill Branch wrote “Their fire, though terrific in sound and producing some consternation at first, did us no damage, as the shells passed over and exploded far beyond our positions.” Colonel John D. Martin, commanding a brigade, reported it “sounded terribly and looked ugly and hurt but few.” Joseph Boyce of the 1st Missouri, serving in Martin’s brigade, called the floating artillery “nothing but noise.”
While the gunboats were not so effective against the main battle line, they affected those close to the river. Company E of 2nd Alabama Artillery lost seven horses, three in one shot. They ended up withdrawing, leaving one cannon in the ravine. The 52nd Tennessee “scattered like sheep” according to William F. Mosier, who served in the regiment. The 10th Mississippi saw men cut down and veered towards the river. Finding the bluffs too high, they only skirmished with Union forces while sniping at the timberclads. Lexington stopped firing at 6:10 and Tyler at 6:25, although if it was due to the 10th Mississippi remains doubtful.
While the gunboats overshot against the main battle line, the shells landed a bit to the rear, where Confederate forces were still forming. The 5th Tennessee ran for cover. Thomas Chinn Robertson of the 4th Louisiana wrote “the shells fell around us like hail and as we could do nothing against the ‘black rascals’, we retreated back about two miles.” Maj. Gen. William J. Hardee, who was even further to the back, thought the fire of the gunboats “was perfectly appalling to our men.” Brig. Gen. Patrick Cleburne, who’s brigade had broken through the Federal center and was poised to attack again, halted. Whether or not most of these regiments could have attacked is doubtful. They were exhausted and in disarray. Yet, it seems the gunboats assured these forces could not promptly form up. If not decisive, Gwin’s guns certainly aided the Federal defense in this regard.
Gen. P.G.T. Beauregard, filling in for Johnston, called off the attack before more regiments joined in. He would have the men rest and then finish Grant off on April 7. Beauregard reported “officers and men were exhausted by a combat of over twelve hours without food, and jaded by the march of the preceding day through mud and water.” In addition, many speculated that Beauregard did not want his men under fire from the gunboats. Maj. Gen. Leondias Polk, one of Beauregard’s corps commanders, thought the roar of Federal artillery, particularly the gunboats with their heavy cannon, convinced Beauregard his men were “waging an unequal contest.” There is not as much direct evidence for Polk’s assessment, but it is possible it influenced Beauregard’s decision. Whether or not the Confederates could have carried Grant’s line is debatable. The terrain was rough, Grant had plenty of artillery, and the Army of the Ohio had arrived, bringing fresh troops, which in turn raised morale in Grant’s battered army. On the other hand, Cleburne at least was well positioned to cause mischief. Regardless, a grander push was never attempted and the Tyler and Lexington played their part.
On the night of April 6, Gwin asked Brig. Gen. William Nelson how he could aid his division. Nelson was an old navy officer, which is likely why Gwin asked him and not Grant or Maj. Gen Don Carlos Buell, commander of the Army of the Ohio. Nelson replied that he wanted wine, cigars, and naval fire every ten minutes into the Confederates lines to keep them awake. Starting at 9:00 Tyler fired every ten minutes. Grant also sent an order for Gwin to fire.
Union naval fire did little damage, but its roar kept many awake, although most reported eventually going to sleep. It did have a psychological effect. Those hit were horribly mangled and some men died in clumps. One shell killed four Confederates playing poker in a Sibley tent, each man apparently still holding their cards when found. Cleburne reported the shells killed mostly Union wounded who were resting on the ground. He fumed that “History records few instances of more reckless inhumanity than this.”
The timberclad pair of Tyler and Lexington survived Shiloh and the war. They were active in many other battles and campaigns, with Lexington saving the garrison at Milliken’s Bend. Yet, both are mostly recalled for their duty at Shiloh. The effect they had has been debated, but it seemed to be a matter of where a soldier was located. What can be said is the gunboats helped repulse the Confederacy’s final push and added to Confederate disorganization and exhaustion on April 7. Gwin’s gunboats were hardly decisive, but certainly a factor in the Union victory at Shiloh.
 Official Records of the Union and Confederate Navies in the War of the Rebellion, 29 vols. (Washington, DC, 1894-1921), Series 2, vol. 1, 227-228. Hereafter cited as ORN. All references are to series I unless otherwise noted; Lanny Kelton Smith, The Battle of Shiloh: The Union Armies, 6 April 1862. (n.p.: Lanny Kelton Smith, 2019), 520.
 War of the Rebellion: A Compilation of the Official Records of the Union and Confederate Armies, 128 vols. (Washington , DC, 1880-1901), Series 1, vol. 10, pt. 1, page 529. Hereafter cited as OR. All references are to series I unless otherwise noted; ORN 22, 762-763; D.W. Reed, The Battle of Shiloh and the Organizations Enraged. (Knoxville, 2008), 53.
OR 10, pt. 1, 204, 466, 622; ORN 22, 763, 764; Boyce, Joseph. Captain Joseph Boyce and the 1st Missouri Infantry, C.S.A. (St. Louis, 2011), 65.
 OR 10, pt. 1, 551; ORN 22, 763-764, 786; Larry J. Daniel, Shiloh (New York, 1998), 254; Mobile Advertiser and Register, April 11, 1862; William F. Mosier, Letter, 52nd Tennessee File, Shiloh National Military Park Confederate Regiment Files; Henry Woodhead, Voices of the Civil War: Shiloh (Alexandria, VA, 1996), 125.
 OR 10, pt. 1, 582; Hardee to Shover April 9, 1862, Felicia Shover Letters, University of North Carolina; Edwin H. Rennolds, A History of the Henry County Commands Which Served in the Confederate States Army (Jacksonville, 1904), 36-37; Thomas Chinn Robertson Letter (4th Louisiana), Navarro College; Timothy B. Smith, “‘Gallant and Invaluable Service’: The United States Navy at the Battle of Shiloh,” West Tennessee Historical Society Papers 58 (2004): 48-50.
 OR 10, pt. 1, 384, 385, 387, 410; Thomas Jordan, “Notes of a Confederate Staff Officer at Shiloh,” in Robert Underwood Johnson and Clarence Clough Buel, ed., Battles and Leaders of the Civil War, 4 vols. (New York, 1884-1888), 1:602-603; Thomas Jordan, and Roger Pryor, The Campaigns of Lieut.-Gen. N.B. Forrest, and of Forrest’s Cavalry (New Orleans, 1868), 135-136; D.C. Kelley, “Mistakes Concerning Battle of Shiloh,” in Confederate Veteran 9, No. 12 (December 1901), 532; Alfred Roman, The Military Operations of General Beauregard in the War Between the States, 2 vols. (New York: Harper and Brothers, 1884), 1:305.
OR 10, pt. 1, 323-324; ORN 22, 764; Ulysses S. Grant, The Papers of Ulysses S. Grant 5 (Carbondale, 1973), 341-342.
 OR 10, pt. 1, 582-583; Daniel, Shiloh, 263; Frank L. Richardson, “War As I Saw It,” Louisiana Historical Quarterly 6, no. 1 (January 1923), 102-103.