He led the fire department during the New York Draft Riots, for which he gained national attention, and later founded the Volunteer Fireman's Association.

He was present at Third Avenue and 47th Street, on Monday, July 13, 1863, when the draft protests turned violent outside the Ninth District Provost Marshal's office.

33 (called "Black Joke," after an 1812 warship) halted the draft selection by smashing the window of the office and breaking the rotating lottery bin.

When a gathering mob set the office on fire, Decker and Black Joke foreman Peter Masterson (a sometime city alderman and state representative) cleared a passage through the mob and enabled the Black Joke to put out the blaze before it burned down neighboring tenements.

No one was appointed in his place as a result and, on the night of August 31, 1865, Decker locked the doors of his office for the last time and went home.

[3] Decker moved to Staten Island in 1867 and later relocated to Port Richmond where he became involved in real estate.

[2] At the 100th anniversary of the British evacuation of New York in 1883, Decker reorganized the surviving members of the old volunteers and assigned them a place in one of the divisions of the Centennial parade.

[1][3] On May 17, 1892, Decker developed symptoms related to blood poisoning in his leg and was confined to his Vreeland Street home.

He last left his residence, walking two blocks to the nearest polling station with the aid of a cane and crutch, to vote for Grover Cleveland in the presidential election of 1892.

His funeral was held at his home the following week, organized by the Volunteer and Exempt Fireman's Associations, and was buried at the Presbyterian Cemetery at New Springville.