John A . Dahlgren John Adolphus Bernard Dahlgren ( November 13 , 1809 – July 12 , 1870 ) was a United States Navy leader . He headed the Union Navy ' s ordnance department during the American Civil War and designed several different kinds of guns and cannons that were considered part of the reason the Union won the war . For these achievements , Dahlgren became known as the " father of American naval ordnance . " He reached the rank of rear admiral . Biography . Dahlgren was born on November 13 , 1809 in Philadelphia , the son of Bernhard Ulrik Dahlgren , merchant and Swedish Consul in Philadelphia . He joined the United States Navy in 1826 as a midshipman and was promoted to the coastal survey in 1834 . By 1847 , he was an ordnance officer , and at the Washington Navy Yard began to improve and systematize the procurement and supply system for weapons . Establishment of U . S . Navy ' s Ordnance Department . He was assigned to the Washington Navy Yard in 1847 . While there , Dahlgren established the U . S . Navy ' s Ordnance Department ; became an ordnance expert ; developed a percussion lock ; and wrote a number of books , including The System of Boat Armaments in the United States Navy , Shells and Shell Guns , and Naval Percussion Locks and Primers . Under his command , the Navy established its own foundry , and its first product was the Boat Howitzer , which was designed to be used on both ship and in landings . Dahlgren gun . But it is his cast iron muzzle loading cannon which came to bear his name ( the Dahlgren gun ) and be his most famous contribution . It was under his direction that the navy established its own foundry to manufacture new equipment . His " shell gun " design was an improvement on the shell - gun invented by the French Admiral Henri - Joseph Paixhans . Dahlgren wrote : The United States Navy had equipped several ships with 8 - inch Paixhans guns of 63 and 55 cwt . in 1845 , and later a 10 - inch shell gun of 86 cwt . In 1854 , the six " Merrimack " - class warships were equipped with 9 - inch Dahlgren shell guns . By 1856 , the Dahlgren gun had become the standard armament of the United States Navy . The boat howitzer derived from a requirement realized during the Mexican - American War . During that war , naval landing parties were armed with a variety of army ordnance , often too heavy and cumbersome for use with the landing boats . Dahlgren first experimented with standard Army issue 12 - pounder mountain howitzers before devising his own system of guns . The boat howitzers came in four basic types : small , light ( or medium ) , and heavy versions of the 12 - pounder and a larger 24 - pounder . All conformed to the same basic shape , straight gun tubes with no adorning bands or clefts . Elevation was made via a screw threaded into the knob at the breech . Instead of by traditional trunnions , the guns were attached to the carriage by a loop under the barrel . The Dahlgren system also included mounting carriages that facilitated various employments of the guns . A single - axle metal carriage was designed for shore use . A bed - type carriage was used on small boats , with a rail system to allow the gun to be trained fore , aft and broadside of the boat . A similar mount was offered for shipboard use . The system of boat howitzers was used by the navy well into the 1890s , with some examples used in ceremonial purposes into the 20th Century . However , fatefully , one of the " dahlgrens " exploded on being tested in 1860 , causing Navy regulations to require the use of much lower levels of powder until 1864 , well into the Civil War . The commander of USS " Monitor " felt that had his gunner packed the cannons with a full charge , he might have been able to destroy CSS " Virginia " . American Civil War . In 1861 , Dahlgren ' s superior at the Navy Yard resigned to join the Confederate navy , and President Abraham Lincoln wanted to name commander Dahlgren to the post of Commander of the Washington Navy Yard . By law , however , that position could only be held by an officer with a rank of captain or above . Lincoln successfully persuaded Congress to pass a special act legalizing Dahlgren ' s appointment to the yard , and , in July 1862 , Dahlgren was promoted to the rank of captain and made chief of the Bureau of Ordnance . Then in February 1863 Dahlgren was promoted to Rear Admiral and took command of the South Atlantic Blockading Squadron . In 1864 , he helped William Tecumseh Sherman secure Savannah , Georgia . Dahlgren ' s son Colonel Ulric Dahlgren was killed during the Civil War in a cavalry raid on Richmond , Virginia , while carrying out an alleged assassination plot against Jefferson Davis and the Confederate Cabinet . The plot is known as the Dahlgren Affair . The admiral was deeply troubled by his son ' s death and role in this event . Despite Radical Republican associations , John Dahlgren ' s younger brother Charles G . Dahlgren ( 1811 – 1888 ) was a strong proponent of slave ownership and was a Confederate Brigadier General , Commander of the 3rd Brigade , Army of Mississippi , which he personally funded . After the Civil War . Dahlgren , took command of the South Pacific Squadron from Rear Admiral George F . Pearson , in 1867 . When he was relieved of the command of the Squadron in 1869 , he returned to the Washington Navy Yard where he served until his death in 1870 . Legacy . The Naval station in Dahlgren , Virginia , Dahlgren Hall at the United States Naval Academy in Annapolis , Maryland , and several ships were named for him , as was Dahlgren , Illinois , and Dahlgren Township , Minnesota . Personal life . Admiral Dahlgren had three sons from his first marriage to Mary Bunker ( 1839 ) . Admiral Dahlgren ' s eldest son , Charles Bunker Dahlgren , was an engineer and captain in the Union Navy . After his father ' s death , he would write and present many technical papers on military weaponry , including the Dahlgren gun . Ulric Dahlgren ( 1842 - 1864 ) was a soldier in the Union Army and was killed in an unsuccessful mission to liberate Federal prisoners in Libby Prison and Belle Isle . Another son , Paul Dahlgren , also in the army , died in 1874 . In 1865 , Dahlgren married his second wife , Sarah Madeleine Vinton , daughter of Congressman Samuel Finley Vinton and Romaine Madeleine Bureau , and the widow of Daniel Convers Goddard , first Assistant Secretary of the newly created U . S . Department of the Interior . Madeleine was a well - known author in her own right . Their children were John Vinton Dahlgren , who married Elizabeth Wharton Drexel ; Eric Bernard Dahlgren , Sr . , who married Lucy Wharton Drexel ; and Ulrica Dahlgren , who married Josiah Pierce , and was the grandmother of Romaine Dahlgren Pierce , wife of David Mountbatten , 3rd Marquess of Milford Haven .