His autobiography, entitled Recollections of a Naval Officer 1841–1865, provides a unique insight into the United States Navy of the mid-19th century during an era when the Age of Sail was coming to an end and the advent of steam power and ironclads was beginning.

William H. Parker became a United States Navy midshipman at the early age of 15, recalling in his biography that he had held his father's hand while being escorted to his first ship.

It was in Buenos Aires that Parker personally met Juan Manuel de Rosas and quickly recognized him as a "cruel ruthless dictator".

Parker states in his biography that he recalls seeing the 7th Infantry Regiment beginning to mass in Florida for the coming invasion of Mexico.

In February 1846, Parker applied to rejoin the crew of USS Potomac and was assigned as a midshipman under the command of Captain John H. Aulick.

It was here that Parker witnessed the Battle of Palo Alto with the assigned naval personnel manning batteries supporting the advancing troops of Winfield Scott.

During the bombardment of Veracruz, Parker was slightly wounded when a bullet grazed his knee and also witnessed his first close quarters casualty when a gunner a few feet away was decapitated by an enemy round shot.

Parker also witnessed extreme bravery from a fellow midshipman, Charles M. Fauntleroy, who would later become an important officer in the Confederate Army.

At the start of June 1847, Potomac departed, under the command of Commodore Perry aboard USS Spitfire, to capture the region of Alvarado.

On June 16, 1847, Parker was transferred to USS Raritan in order to participate in the expedition and volunteered to serve in a formation of naval pioneers being sent ashore to capture Tabasco.

Again arriving to find the town already surrendered to a pair of steam gunboats, Parker returned to Raritan, which then set sail for Norfolk, Virginia.

The conflict on the Gulf Coast came to an effective end when Mexico City fell in September 1847, and a peace treaty was signed the next year in February 1848.

In August 1847, Parker was detached from USS Raritan and placed on leave; he spent the time visiting his father in Boston before reporting to the United States Naval Academy in September.

The school then being just a few years old, and most of the students coming from at-sea assignments, Parker was placed in an advanced curriculum with graduation scheduled for the next summer.

In February 1849, Yorktown sailed to Liberia, where she participated as an observer in a Liberian attack against several native tribes living in the interior jungle.

It was here that Parker met the President of Liberia (Joseph Jenkins Roberts) who traveled as a guest of honor on board Yorktown.

In the summer of 1851, Parker spent three months on leave and then reported to USS Washington, which was then assigned to perform coastal survey duties.

For the remainder of the summer, Parker sailed with the Washington along the Nantucket Shoals, surveying such areas as Block Island and the so-called "No man's land".

Parker's feelings were somewhat prophetic, since Princeton would in fact suffer a major accident several months later when one of its guns exploded and killed several high-ranking dignitaries who were then on board.

During this same period, Parker met the Vice President of the United States (William R. King), who was then traveling aboard USS Fulton.

The ship, USS Preble, visited the ports of Eastport, Cape Cod, Portland, and Boston before returning to Annapolis in the fall.

On October 17, 1857, Merrimack sailed from Boston on a mission to the United States Minister to Brazil (Richard Kidder Meade) to his new assignment.

The ship made port in Rio de Janeiro in December 1957 and then proceeded to round Cape Horn to enter the Pacific Ocean at the start of the new year.

At the end of February, the ship put into port in the small coastal town of Callao with shore leave authorized for the crew.

Parker took the opportunity to travel to Lima, where he witnessed "some type of revolution" which was underway under the leadership of Lizardo Montero Flores.

It was at this time that the crew was informed of the John Brown Raid and, according to Parker's biography, he had already come to the conclusion that civil war between the North and South was inevitable.

After several months' shore duty, First Lieutenant Parker was sent to Charleston, South Carolina, where he was executive officer of the ironclad CSS Palmetto State and participated in her attack on Union blockaders in January 1863.

In October 1863, he became superintendent of the Confederate States Naval Academy, based on board CSS Patrick Henry in the James River, Virginia.

In April 1865, as the Confederate capital at Richmond, Virginia was evacuated, he led the Naval Academy's midshipmen as a guard for their failing Government's archives and treasury.

Recognized as a "hopeless drunkard" by the chargé d'affaires, George Clayton Foulk, Parker was relieved of his position less than a year later.