Unless stated otherwise, all information herein is taken from The World of Robert Jordan's "The Wheel of Time", Chapter 4.
The drilling of the Bore was done by a research team from Collam Daan university, led by Mierin Sedai (later Lanfear) with help from Beidomon Sedai. They had discovered a Power emanating from a specific area. This power could be drawn by both male and female channelers, which would solve the difficulties arising from the necessity of working with saidin and saidar. Unfortunately, though they did not know it at the time, this was in fact the Dark One's True Power. The Sharom, a floating white sphere a thousand feet in diameter (TSR, Ch. 26), was used to perform the drilling. The drilling resulted in ripples throughout the fabric of reality itself, which sent shockwaves into the Great Pattern. For the first time in this Age, the Dark One could touch the world. This resulted in corruption of human minds by an evil unknown at the time. Society oozed with envy and other evil impulses. Chaos and violence erupted more frequently. This decline of the once idyllic society is known as "the Collapse".
Toward the end of the War of the Shadow, Lews Therin developed a plan to defeat the Dark One by sealing up the Bore. Due to dangers associated with it, none of the female Aes Sedai were willing to take part in this plan. As a result, it was a group of all-male channelers, the Hundred Companions, who placed the seven seals and ended the war. The strike took place in Shayol Ghul, the place where the erosion of the pattern was most significant.