Dahlgren was born in 1809, in Philadelphia, Pennsylvania, the son of the Swedish consul in the city. He joined the US Navy in 1826 as a midshipman, but in 1834 went to work on a survey of the US coast line. In 1839, he married Mary Bunker, and they had seven children before her death in 1855. By 1847, Dahlgren had become an ordnance officer, and, serving at the Washington Navy Yard, was intent on improving the procurement and supply system for weapons. There, he established the US Navy’s Ordnance Department; developed equipment (not least the Dahlgren gun); and authored various books, including The System of Boat Armaments in the United States Navy, Shells and Shell Guns, and Naval Percussion Locks and Primers. He also established the Navy’s first foundry to manufacture new equipment - its first product being the boat howitzer, designed for use aboard ship and in landings.
With the onset of the Civil War, Dahlgren was appointed by Abraham Lincoln as Commandant of the Washington Navy Yard, a key post for ordnance and for defence of the city. He worked in close contact with Lincoln and many of his cabinet. He was soon promoted to captain and, in 1863, to rear admiral in command of the South Atlantic Blockading Squadron. He led a partially successful naval assault on Charleston, and later participated in the final occupation of that city; he commanded an expedition up the St. John’s River in Florida; and he cooperated with Sherman in the capture of Savannah.
After the war, Dahlgren spent some years as commander of the South Pacific Squadron. In 1865, he married his second wife, Sarah Madeleine Vinton, daughter of a Congressman, and they had three children. He, finally, returned to his old positions as Chief of Ordnance and Commandant of the Washington Navy Yard. He died on 12 July 1870. Further information is available from Wikipedia, Syracuse University, Naval History and Heritage and Mr Lincoln’s White House. Also, freely available online, is The Autobiography of Rear Admiral John A. Dahlgren published by Naval History and Heritage Command in 2018 (pdf).
Dahlgren kept detailed diaries from his mid-20s until his death. These are held, along with a large archive of his papers, by Syracuse University Libraries. They are described as follows:
‘The writings of John A. Dahlgren himself, including thirteen volumes of his diaries and one journal, form the bulk of this section. Dahlgren’s diaries, which date from 1834 to 1870, were kept with great regularity and in extensive detail. The volumes from the Civil War years are especially notable as rich sources for information on the war generally, on its naval and ordnance aspects, and on Abraham Lincoln.
In the early years of the war, before his reassignment to the Atlantic Squadron took him away from Washington, Dahlgren was quite close to Lincoln. His diaries note numerous dinners at the White House, outings with Lincoln by carriage or boat, any many meetings and conferences. There are frequent entries recording Lincoln’s opinions of various generals, his interest in modern weaponry, his problems with his cabinet and Congress. Dahlgren also describes Lincoln at ease, taking breakfast in his drawers and telling stories, or cruising up the Potomac and test-firing one of the “Dahlgrens” himself. He often quotes or paraphrases Lincoln.
The diary pages contain mention of many other famous men of the Civil War, including Stanton, Chase, Wells, Sherman, McClellan, Ericsson and others whom Dahlgren knew. Even when he was not personally involved with an individual or an event, Dahlgren often wrote a well-informed account of opinion in these volumes. He wrote extensive discussions of strategy and new developments in weapons and ammunition, and occasionally he wrote about the political and social aspects of the war. In the years preceding and following the Civil War, Dahlgren’s diaries form a record of his naval assignments and ordnance work, as well as of his family and personal life.
Dahlgren's single journal, the daily record of a specific activity stems from his 1829 cruise on the U.S.S. Ontario to the Mediterranean.’
Dahlgren’s diaries were used extensively by his widow in compiling Memoir of John A. Dahlgren, Rear-Admiral United States Navy (published by James R Osgood, 1882) - freely available to read online at the Hathi Trust. The book is divided into three parts - The Navy of the Past, Ordnance Record, and The Rebellion - and into 20 chapters. Three of these chapters have titles referring directly to Dahlgren’s ‘Private Journal’ but many of the other chapters are also no more than transcripts of the diaries. Here are several extracts.
3 Feb 1862
‘The public is disquieted with apprehension of British intervention. How stands the game? It is one year since five of the Cotton States seceded from us. The Northern States have an army of 600,000 men in the field. The Navy has been expanded so as to command the Southern seaboard. We hold a point on the coast of North Carolina, one in South Carolina, and one in Florida. In a word, we are just prepared to move, and only wait on the weather. The first weather that freezes the road hard, ought to be the signal. Will it be?
The opportunity for decision seems brief, from two causes, - one financial, the other political. A debt of not less than five hundred millions has been incurred for this preparation, without the first step to provide for it; so the public credit has been used to its full extent, and we are threatened with want of funds.
The other difficulty is from abroad. England cautiously but surely progresses towards intervention. . . Mason and Slidell are demanded by an ultimatum, and now we have threats of
more direct interference, for which purpose she does not relax in preparation for war. . . It is now evident that the pivot of affairs lay in the period beginning at the time when the attack of Sumter was decided, and the abandonment of Norfolk. The loss of Norfolk was almost fatal; could that have been held, the fate of Virginia might have been otherwise.
The Department had one month to send there a suitable Commandant and officers, which was not done. So the latter deserted and the former was helpless.
How much has it cost, only to ward off the consequences of this mistake! . . .’
5 February 1862
‘The Presidential Reception came off this evening, as appointed. The President and Mrs. Lincoln received in the East Room. The only distinction between this soirĂ©e and the usual reception was, that the guests were selected by invitation and there was a supper. It so happened, I was the only Navy officer present. The officers of the Army, below the rank of General of Brigade, with one or two exceptions, were not there.
All the Foreign Ministers were present.
About midnight the President led the way to the supper-room, which was said to be the most superb thing of the kind that had been seen in Washington. . . While the supper was going on, I fell in with General McClellan. He whispered to me that Fremont was in the room. This is the first occasion I have heard of Fremont’s appearance in such places. The General admired my sword very much; for, being in full uniform, I wore that presented by the Seventy-first. I observed the niece of Mrs. McClellan with General Stone. Four days afterwards General Stone was arrested for treason and sent to Fort Lafayette.
2 April 1862
‘I went down to Mt. Vernon with the President, some members of his family, and others. I advised the President not to land, and remained in the boat with him. General McClellan went down yesterday. Troops still going. Must be nearly 100,000 men at Old Point.’
5 April 1862
‘Great events are at the threshold. The army has begun to move from Fort Monroe, more than 100,000 men, with McClellan at the head, thus changing the first view, for McDowell was to operate here with some 50,000 men. Now he is left behind, and the Chief goes in command, converting the subordinate into the main movement. So it is Richmond, now or never.
Again the “Merrimac” is supposed to be refitted, and her movements will be watched with much solicitude.
In the West the principal armies are about to fight a battle which will decide the fate of Memphis and much else. . .’
24 February 1864
‘In came the “Harvest Moon,” a sea packet, new and just bought, side wheels, and very like the “Philadelphia,” save that she could go to sea. I will go North in her. . . I have news that our troops have been regularly trapped on the march inland from Jacksonville, and lost 1,200 men in battle, besides being beaten.’
25 February 1804
‘Moving from the “Philadelphia” to “Harvest Moon.” I sent for Rowan; Rowan came. He asked “If they blew up a monitor, what he should do?” I answer, “Do not let them, and take care of the rest.” “Well, but shall I go outside?” “ Follow your judgment, and inform me immediately.” We crossed the bar at eleven. . . Got to Port Royal after sunset.’
26 February 1804
‘I went to see General Gillmore. Had a long talk. He said he only landed 3,000 men on the day we entered upon Morris Island. The most he had at any time was 10,000, but then thirty-seven per cent were sick and not fit for service. One day, on collecting all his force, he had 6,300 out of the 10,000. He also thought that Johnson was complete at the landing, but the batteries between it and Seceshville, Simpkins, Hascall, and Cheves, were put up after the landing. Said he gave up the steamer “Mary’s,” as I had the law of him. Spoke of the defeat in Florida, 700 killed, &c, and several hundred slightly wounded. He said Seymour had gone beyond his instructions. Said he had dismissed one correspondent of ____ for lying, who in excuse said he had to do so, and now another had been guilty of slandering. . . Showed me the drawings and model of Wagner and its approaches. Spoke of his idea of engineering across James Island. I told him I was called home for a few days by the Department. Said he would come to see me this evening. Gillmore is an engineer, but no general. About eight, Gillmore came off with Colonel Fuller, the new Quartermaster. He said I might repeat to the authorities what he said.’