CLARENCE ELLSWORTH McMULLEN was born in Blue Bell, Maryland on November 11, 1895 to Robert and Amelia McMullen. The 1900 Census shows the family in Calvert, Maryland. They moved to Camden after the 1906 Camden City Directory was compiled.

The 1910 Census shows the family living at 223 Royden Street in South Camden. Besides Clarence the family included older siblings Viola and Harry, and younger sister Alma. By 1914 they had moved to 205 Royden Street. The family was still at that address when the 1918-1919 Camden City Directory was compiled. Clarence McMullen was then serving in the United States Army. The McMullens were still living at 205 Royden Street when the Census was taken in January of 1920. Clarence McMullen had returned home from the Army and was working as a shipfitter in one of Camden's shipyards.

The 1924 Camden City Directory and the April 1930 Census shows Clarence McMullen at 323 Warren Avenue. Clarence McMullen had been appointed to the Fire Department on March 1, 1930. He was assigned to Engine Company 2, where he worked until March 10, 1943 when he was reassigned to Engine Company 7. On January 1, 1950 he was transferred to Engine Company 9 in East Camden.

By 1931 Clarence McMullen bought a home at 486 North 35th Street. He rented an apartment in the late 1930s and early 1940s to brother firefighter John McKay. 

Shortly after 7 A.M. on May 23, 1941, a Box was transmitted for a fire at West and Clinton Streets, South Camden. Arriving companies found a three-story commercial building with fire roaring one hundred feet into the sky. A second alarm was transmitted on arrival, followed by third and fourth alarms ordered by Chief John Lennox. The building contained a food market on the ground floor and a clothing factory above. At the height of the blaze, Firemen Clarence McMullen and James Creato narrowly escaped with their lives after a burst of flame nearly enveloped them as they forced an interior door to a shaft. Both members fought their way out under the cover of hose streams directed by their comrades. Chief of Department Lennox and four firemen while at the far end of the blazing building on West Street, heard the shrill cries for help coming from a nearby dwelling. Racing into the home of Mrs. Elizabeth O'Hanlon at 423 Clinton Street, they found an excited albeit unscathed parrot, in a kitchen birdcage still crying for help. The bird was carried to safety by the firemen. The blaze was brought under control at 10:30 A.M. but not before heavily damaging the block long building. 

Clarence McMullen was still living at 486 North 35th Street when he retired on pension on June 26, 1960. He was still living in Camden when he passed away in September of 1983.