Matthew B. Gilmore
Washington was founded with civic celebration in mind and there’s none better than a parade. Pennsylvania Avenue has hosted most of these, including the presidential inaugural (such as seen in this rare footage of McKinley in 1901) every four years, although some parades have now been shifted to the more spacious Constitution Avenue.
Military parades have long been a vital part of Washington ceremonial, only recently has the tradition slipped into disuse. The greatest parade has to have been the Grand Review of the Army at the conclusion of the Civil War. It spanned two days, May 23 and 24, 1865. President Andrew Johnson and General Ulysses Grant presided, President Lincoln having been assassinated several weeks previous.
The grand review of the Army. Presidential reviewing stand with guests and guard. Brady, Mathew B., ca. 1823-1896, photographer LC-B811- 3304 [P&P] LOT 4198 (corresponding print) Civil War photographs, 1861-1865 / compiled by Hirst D. Milhollen and Donald H. Mugridge, Washington, D.C.: Library of Congress, 1977. No. 0841.
“Shermans’ Grand Army. Looking up Penn. Ave. from the Treasury Bldgs. A portion of the 20th Army Corps passing in review.” May 24, 1865. Brady, Mathew B., ca. 1823-1896, photographer. LC-B811- 3397 [P&P] LOT 4198 (corresponding print)
Recreation in 2015 from C-Span: https://www.c-span.org/video/?326092-1/grand-review-parade
Civil War veterans would return periodically throughout the 19th century to Washington as part of the Grand Army of the Republic National Encampment.
In 1916 as a kind of preamble to war Washington had a “Preparedness Day” parade.
Floats included this one with torpedoes:
Preparedness Day parade float with torpedoes, 1916. Creator(s): Harris & Ewing, photographer. LC-H261- 6192 [P&P]
Other floats featured other weaponry:
Preparedness Day Parade float, 1916. Harris & Ewing, photographer. LC-H261- 6358 [P&P]
The next grand military parade was for Armistice Day and the government went all out, even (emulating New York City) erecting a triumphal arch at the intersection of 15th Street and Pennsylvania Avenue under which the troops processed.
Soldiers returning from World War I parading through Victory Arch on Pennsylvania Avenue in Washington, D.C., Oct 13., 1919. LC-USZ62-78370 (b&w film copy neg.) LOT 8885 [item] [P&P]
Throughout the 20th Century the various service branches had public celebrations. In 1922 Navy Day was instituted on October 27, the birthday of Theodore Roosevelt. For 22 years ceremonies took place across the country and at the Navy Yard in Washington. In 1944 Navy Day was celebrated with a parade on Pennsylvania Avenue.
Defense Day was instituted in 1924, and a parade held September 12.
Defense Day parade on Pennsylvania Avenue, September 12, 1924. National Photo Company Collection LC-F8- 32326 [P&P]
Army Day was instituted in 1928. In 1933 the day was celebrated with a parade.
In 1939 President Franklin Roosevelt again presided over the review, which featured tanks. Cavalry had been featured in previous parades but mechanized warcraft was rarer.
Latest types of tanks rumble past The Capitol in Annual Army Day Parade. Washington, D.C., April 6, 1939. Memories of the World War were revived today as the latest types of tanks, preceded by 20,00 soldiers and veterans, paraded past the U.S. Capitol in the Annual Army Day Parade which marked the 22nd anniversary of America into the World War. Thousands braved a heavy downpour to view the parade. Harris & Ewing, photographer LC-H22-D- 6280 [P&P]
President Roosevelt Reviews Army Day Parade. Washington, D.C. April 6, 1939. President Roosevelt Led the Nation Today in Observing Army Day as He Reviewed a Colorful Parade Comprised of Virtually Every Arm of The Service. Rumbling of The Giant Tanks Revived Memories of America’s Entry into The World War Twenty-One Years Ago Today. In the Stand Can Be Seen, L To R: Brig. Gen. William F. Bryden, Grand Marshal of The Parade; President Roosevelt; Brig. Gen. Albert Cox of The D.C. National Guard; And Assistant Secretary of War Louis Johnson. Harris & Ewing, photographer. LC-H21- C-838 [P&P]
In 1949 Army Day was abolished after the parade (seen here: Army Day In Washington (1949) https://www.youtube.com/watch?v=AhVqG8uc4T8 ) in favor of a joint celebration — Armed Services Day.
Most recently the end of the Gulf War was celebrated June 8, 1991 with a parade down Constitution Avenue–C-SPAN coverage: https://www.c-span.org/video/?18328-1/national-victory-celebration-parade
Addendum: interesting Mother Jones piece on American military parades (mostly elsewhere than Washington): https://www.motherjones.com/politics/2018/02/actually-the-us-has-a-rich-tradition-of-military-parades-but-normally-theyre-after-military-victories-and-stuff/