Algert Daniel Alexis was born in Minersville, Pennsylvania on 25 June 1897, son of William and Helen Elizabeth (Kell) Alexis. He attended public schools in Minersville and Lafayette College, Easton, Pennsylvania, from which he received a degree in Civil Engineering in 1919. Appointed Assistant Civil Engineer with the rank of Lieutenant (jg), in the US Navy in September 1921, he was commissioned in September 1922 as Assistant Civil Engineer with the rank of Lieutenant. He subsequently advanced in rank, attaining that of Rear Admiral to date from 11 September 1943. On 1 January 1954 he was transferred to the Retired List of the US Navy.
After his appointment in the US Navy in 1921, he was assigned to the Third Naval District where he had duty until May 1924 as Assistant to the Public Works Officer, and additional duty at the Navy Yard, New York, and later at Sayville, Long Island, New York. He was next ordered to the Naval Operating Base at Hampton Roads, Virginia, and in October of the following year was transferred to Port au Prince, Haiti, where he served under the Engineer in Chief, Republic of Haiti, as Department Engineer of the South and as Director of Roads, Bridges and Harbor Works. During that period he had temporary additional duty with the First Brigade, US Marines in Haiti.
Between October 1929 and June 1934 he had duty in the Eleventh Naval District, Headquarters at San Diego, California, under the District Public Works Officer. There he was Project Manager for the Destroyer Base, Naval Hospital and Radio Station. He then reported to the US Naval Station, Samoa, where was assigned for two years as Public Works Officer and Superintendent of Public Works for the Island Government. In February 1936 he became Assistant Public Works Officer of the Sixth and Seventh Naval Districts and the Navy Yard, Charleston, South Carolina, and in May 1940 was transferred to the Twelfth Naval District, with headquarters in San Francisco, California.
On 1 March 1941, he became Officer in Charge of Construction at the Naval Supply Depot and Dry Dock, Bayonne, New Jersey, and in March 1942 reported as Public Works Officer in Charge of Construction, Thirteenth Naval District, with headquarters in Seattle, Washington, and in addition had similar duty for the Alaskan Sector. From April 1943 until July of the following year, he was Director, Alaska Division of the Bureau of Yards and Docks, and in that assignment was concerned with construction of Naval Bases in Alaska by the Seabees. For "exceptionally meritorious" services in that capacity, he received a Letter of Commendation, with authorization to wear the Commendation Ribbon, from the Secretary of the Navy.
In August 1944 he became Officer in Charge of the Advanced Base Depot, Port Hueneme, California, and was responsible for the assembly and shipment of construction equipment and supplies for Seabees. Preceding the Japanese surrender, he served with Commander Service Force Pacific Staging, Sixth Construction Brigade, preparing for landing of 30,000 Seabees and construction on Japanese Islands. For several months after VJ Day, he headed a Property Disposal Unit to study and recommend disposal of surplus Navy property and disposition of Navy supplies to the Navy's permanent bases.
In December 1945 he reported as Public Works Officer of the Norfolk Naval Shipyard, Portsmouth, Virginia, and Officer in Charge of Construction. In 1948 he became District Public Works Officer, Fifth Naval District, Norfolk, Virginia. He remained in that assignment until July 1950, when he became Director, Atlantic Division, Bureau of Yards and Docks, New York, with additional duty on the staff of Commander Eastern Sea Frontier, and on the staff of Commander in Chief, US Atlantic Fleet. He served in that capacity until relieved of all active duty pending his retirement, effective 1 January 1954.
In addition to the Commendation Ribbon, he had the Diploma of Honor and Merit from the Republic of Haiti, and was entitled to the American Defense Service Medal; the American Campaign Medal; the Asiatic-Pacific Campaign Medal; the World War II Victory Medal; and the National Defense Service Medal.
The honorary degree of Doctor of Science was bestowed upon him by Lafayette College in October 1953. He also was a member of the honorary engineering fraternity of Tau Beta Pi, American Society of Civil Engineers, Society of American Military Engineers, Naval Order of the United States, and Naval Institute.