It started when the wooden lining of the mine shaft caught fire and ignited the coal breaker built directly overhead.

These conflicts eventually resulted in the trial and execution of twenty members of the Molly Maguires in Pottsville and Jim Thorpe.

[5] The Steuben Shaft at Avondale Colliery is situated on the right bank of the Susquehanna River, four miles from Plymouth Township, Pennsylvania in Luzerne County.

[7] The Steuben Shaft seemed to have been a disaster waiting to happen, but this was state-of-the-art construction for American deep-shaft coal mines at the time.

However, not everyone has accepted the theory, so ethnic conflict between Welsh and Irish workers, industrial espionage, and spontaneous combustion have also been considered as possible causes.

James M. Corrigary, the writer of a research paper on the incident, described it as such: "Imagine a plane of fire running up at an angle of about thirty-three degrees toward the hill above, and after it has accomplished that distance, see it shoot up in one immense column into the air, while dense clouds of smoke envelope all surrounding objects, and the reader can have a faint idea of the spectacle.

As soon as the flames had been extinguished sufficiently for rescuers to approach the shaft, preparations were made to put a derrick over the opening by which men could descend into the mine.

[14][15] Before the dog had been lowered into the shaft a number of men had called into the mine, hoping they would receive an answer from the imprisoned miners.

A volunteer, Charles Vartue of the Grand Tunnel colliery, was then asked to descend into the mine and report on the conditions inside.

[14] More volunteers were requested, and Charles Jones of Plymouth and Stephen Evans of Nottingham Shaft were selected to be lowered into the mine.

[14] Later in the evening another two volunteers, Thomas W. Williams of Plymouth and David Jones of Grand Tunnel, decided to enter the mine to discover the condition of the men within.

[16] The presence of toxic levels of blackdamp made rescue efforts much more complicated, as nobody could stand the increasingly foul air for long periods of time.

[14] The overwhelming presence of lethal levels of blackdamp augured little hope for the 108 trapped miners; rescue attempts yielded to recovery operations.

Since normal ventilation had been blocked by debris in the shaft and main gangway, blackdamp and whitedamp (carbon monoxide from incomplete combustion) continued to be produced at lethal levels by the furnace.

By heroic efforts, the fire was extinguished with water piped from the surface, using the 300-foot pressure head as a natural motive force.

The brattice was constructed by the desperate trapped miners attempting to stop the infiltration of blackdamp, in the hope of surviving on cleaner deep mine air until rescue.

Many victims appeared merely to be asleep; fathers embraced their sons, men assumed the attitude of prayer, others leaned against gangway walls.

On Saturday, September 11, 1869, a Coroner's inquest concerning the cause of the death of the victims of the disaster began at Shupp's Hall, Plymouth.

The inquest had to deal with a crushing irony: The nascent anthracite miners' union, The Workingmen's Benevolent Association (WBA, founded 1868 by John Siney), had successfully petitioned the Pennsylvania State Legislature for the passage of a new mine safety act, which became law on April 12.

Much testimony centered around the lack of a second exit and absence of deep mine air shafts, unsafe storage of combustibles, and a history of fires.

I consider it relative no more danger getting on a railway train and riding one hundred miles than working in that mine.The position of the union was made dramatically clear by representative Henry Evans: In answer to a question from Mr. H. W. Evans, [an unidentified] witness said, "That seems intended to bring out a condemnation of the system of mining with but one outlet; I fully agree in condemning that system."

After deliberation, the Jury delivered its verdict: An inquisition at Plymouth, in the County of Luzerne, the eighth, ninth, eleventh, and fourteenth days of September, in the year of our Lord, one thousand eight hundred and sixty-nine,...do say upon their oaths that...The cause of death of Palmer Steele [a miner] and other people sustained was the exhaustion of atmospheric air and the presence of the abundance of carbonic acid gasses in the said Avondale mines, caused by the burning of the Head House and Breaker at said mine, on the sixth day of September 1869, destroying the air courses leading from the mine through the shaft.

That the fire originated from the furnace in the mine, taking effect on the wood brattice to the up-cast air course leading from the bottom of the shaft to the Head House.

The jury regards the present system of mining in a large number of cases now working by shaft as insecure and unsafe to the miner, and would strongly recommend, in all cases where practicable, two places for ingress and egress and a more practical means of ventilation, thereby rendering greater security to the life of the miner under any similar accident.