Sinking began in 1891 by the Universal Steam Coal Company, a subsidiary of the Lewis Merthyr Consolidated Collieries Ltd.
The two shafts named Lancaster (downcast) and York (upcast) were each 650 yards deep and production began in early 1896.
From the Inspector of mines list 1896, there were only 236 men employed.
By the turn of the century this colliery was producing 200,000 tons of coal per year.
A powerful gas and coal dust explosion on Friday May 24th, 1901, killed 81 of the 82 men underground at the time. It occurred around 5.00 am in the East side of the pit about 700 yards from the pit bottom.
A rescue attempt could not immediately go ahead because of the damage sustained to both shafts. The cage in the Lancaster shaft was jammed making it inoperable, so the rescue work concentrated on the York pit it took five hours to clear the debris at the bottom of the other shaft before the cage could be landed.
The sole survivor an ostler, William Harris was found unconscious lying by the side of a dead horse about 50 yards from pit bottom. He was badly burned about the face and hands and at first his rescuers believed him dead.
The ferocity of this explosion caused a tremendous amount of damage to the fabric of the colliery, blasting away roof supports causing huge roof falls. It took several weeks to recover all of the bodies, many of which were unable to be identified.
In 1908 there were 1,440 men employed.
As bad as the 1901 disaster had been it was to be overshadowed by the biggest mining disaster in Great Britain, which occurred at this colliery on Tuesday 14th of October 1913, killing 439 miners.
It was 8 o’clock in the morning with a workforce of 950 men underground when there was a massive explosion, the force of which sent the cage in the Lancaster pit rocketing up the shaft and crashing into the pithead gear. The force of the blast smashed the wooden platform on which the banksman John Mogridge was standing; he was decapitated by a large splinter of timber.
There had been little damage to York pit, so the manager and some other men slowly descended this shaft. When they reached about 530 yards down some girders blocking their progress halted their descent, but by shouting down the shaft to the nine-foot level they were heartened by the replies that some of the men were safe.
Soon the Mines rescue teams from Crumlin, Aberdare, Porth and the Rhymney valley were at the scene but their rescue attempts were badly hampered by raging fires, thick smoke and roof falls. One of the rescuers William John was killed when part of the roof caved in.
Later the same day at 11.30 pm an advanced party of rescuers managed to make entry into the Bottanic district and there they found a man and a young boy alive and unharmed. By 1.00 am the following morning a group of twelve trapped miners were found alive behind a roof fall. A short distance away another four were found unconscious but still alive. Twenty dead bodies were also recovered from this district.
When the rescued were brought to the surface they were greeted with shouts of joy from the waiting crowds, who were filled with new hope that more of their loves ones might be found safe.
But as each day went by with no further survivors being found all hope gradually diminished.
The rescuers were continually hindered by further outbreaks of fire, huge roof falls and blowers of gas and even after three weeks had past only a third of the victims had been brought to the surface.
Eventually the rescuers reach the districts known as Ladysmith, Pretoria, Mafeking and Kimberly where the majority of the bodies were found.
Over 90 bodies were so badly mutilated by the blast of the explosion or the ensuing fires that they could not be recognised, their items of clothing only identified some. One young boy’s identity was only confirmed when his mother recognised a patch that she had sewn into his vest and another by the champagne cork in his water jack, given to him by one of his butties (friends). Another victim, Aaron Manders wore his new boots to work for the first time on that fateful day, it was those boots that established his identity.
Nearly every household in Senghenydd had lost somebody and it was estimated that 1500 dependants were left without a breadwinner.
After the Court of Enquiry the Chief Inspector of Mines, R. A. S. Redmayn CB, in his report concluded: The only apparent means of ignition would be sparks from the electric signalling apparatus, or from rocks brought down by a fall.
This contrasts with the verdict of the jury at the Coroners Inquest, who when asked by the Coroner, David Rees, “Where did the explosion originate” they replied, “There is insufficient evidence to answer definitely; but the preponderance of evidence points to the lamp station as the probable vicinity where it originated.”
During the enquiry several breaches of regulations were uncovered, the most serious of these was the inability of the ventilating fans to reverse the airflow. Legislation had required that all mines should have implemented this by January 1st 1913. It was estimated if the current of air had been reversed a hundred lives might have been saved.
This information led to 17 charges against the colliery manager and four against the company. These charges were first heard at Caerphilly Magistrates Court on the 5th of May 1914. After a number of adjournments the Magistrates finally gave their decision on the 18th of July 1914.
To the disbelief of the miners, their union and the mines inspectorate, the amount of fines given to the mine owners and the manager totalled £24.
There was countrywide condemnation of the courts decision and one local newspaper’s headline read “Miners lives at 1s 11/4d each” .