Chase had designed and constructed the fort while he was a captain in the United States Army Corps of Engineers.

An informal truce between the administration of President James Buchanan and Florida officials, including their still sitting U.S.

His entire military service to the emerging Confederate cause occurred during the secession crisis prior to the Battle of Fort Sumter.

Chase, a United States Military Academy graduate, served in the U.S. Army Corps of Engineers from 1815 to 1856.

After his retirement from the U.S. Army, he was a slave owner, banker, president of the Alabama and Florida Railroad Company and writer in defense of the merits and importance of the cotton economy.

After his role at the beginning of the Fort Pickens confrontation, the 62-year-old Chase returned to the operation of his business interests and took no part in the Civil War.

[2][3] Chase spent almost all of the remaining 38 years of his U.S. Army career working in the Gulf Coast States.

[3] Chase began his duties in the Southern States as an assistant engineer in construction of Fort Pike, Louisiana in 1819–1822.

[2][3] He was assigned as superintending engineer of the defenses of the Rigolets and Chef Menteur Passes of the Mississippi River in 1822.

[2][3] Between 1824 and 1828, he was superintending engineer of forts at the Rigolets, Chef Menteur, Bienvenue and Bayou Dupre Passes to New Orleans.

[6] In 1844, Chase began service on special boards of engineers for examination of various improvements, including Florida Reef in 1844–1845; the Gulf frontier of Mississippi and Texas in 1845; briefly, the Atlantic Coast Defenses in 1848; the Memphis Tennessee Navy Yard in 1851; the floating dock and other improvements at the Pensacola Navy Yard in 1851; the United States Custom House at New Orleans in 1851; and the Passes of the Mississippi River and Harbor at Lake Pontchartrain in 1852.

[3] This assignment engaged Chase in the construction of the second of the three Florida forts which remained under the control of the Union Army throughout the Civil War.

[1] One historian states that Chase's refusal of the West Point appointment was due to his immersion in his business interests at Pensacola.

[1][2][3] Chase published several tracts on engineering matters, including a joint publication with other officers concerning levees on the Mississippi River, as well as a promotional pamphlet on Pensacola real estate sales.

[1][3] Following his resignation from the U.S. Army on October 31, 1856, Chase operated his business interests in the Pensacola area, was a city alderman for Pensacola and wrote nationally syndicated articles promoting the power and importance of the cotton economy, "King Cotton.

[1][16] Just three weeks after South Carolina had passed an ordinance of secession, Florida became the third State to secede from the Union.

Florida Governor Madison Starke Perry appointed William Henry Chase as colonel of the Florida militia to command forces ordered to seize the federal forts and property around Pensacola because of his intimate familiarity with the property and his former position as a senior U.S. Army officer.

[27] Lieutenant Gilman reported that Chase said he wanted to avoid bloodshed and that he had written his demand in proper form and would read it.

[29] Chase said that Slemmer must know that Florida could not permit the fort to be held and that an attack would start a civil war.

[17] The official papers of President Abraham Lincoln contain a letter dated June 20, 1861 from the President through United States Secretary of State William Seward to then General-in-Chief Brevet Lieutenant General Winfield Scott in which he suspends the writ of habeas corpus with respect to "Major Chase, lately of the Engineer Corps of the Army of the United States, now alleged to be guilty of treasonable practices against this government.