Dealings with Vinny Lavecchia
One evening in 1959, Sebastian Shaw met with Las Vegas crime boss Vinny Lavecchia at the Hellfire Club. After a game of cards, Lavecchia attempted to extort Shaw for money and wanted in on his dealings with Colonel Hendry. While they were conversing, Lavecchia's men killed Shaw's guard Rocco and planted a bomb in his office. 
Lavecchia enlisted the help of his personal telepath, Emma Frost, to probe Shaw's mind for information. Emma was startled by the fact that Shaw was a mutant like herself. When Shaw still refused to do business with Lavecchia, the mob boss angrily stormed out of the Hellfire Club, threatening to make Shaw pay. 
Outside, Lavecchia confirmed with his men about the bomb's plantation. He ordered them to chain the doors of the Hellfire Club and kill anyone who survived. After Lavecchia departed, his men waited behind for the bomb to detonate. Unbeknownst to them, Shaw's mutant ability allowed him to absorb the bomb's energy, which he then used to kill Lavecchia's men. The energy caused the Hellfire Club to be engulfed in flames, prompting Shaw to order Riptide to put the flames out. Following this, the Hellfire Club was remodeled and became "Atomic". 
Dealings with Colonel Hendry
In 1962, Shaw hosted a party at Atomic where he invited three mob bosses, the Italian ambassador, the CEO of a company called Lockheed, and United States Army Colonel Robert Hendry of NATO. Shaw had Emma Frost bring Colonel Hendry to private room so he could talk placing Jupiter missiles in Turkey, which would incite a nuclear war that could render humans extinct and mutants as the dominant species on the planet. When Hendry refused, Shaw had Riptide and Emma reveal their powers to Hendry as a means of coercion. Following this, Shaw ordered Azazel to teleport Hendry to the Pentagon, where the colonel voted in favor of placing the Jupiter missiles in Turkey. However, unbeknownst to Shaw or his associates, they were being investigated by CIA agents Moira MacTaggert and Levene. Moira had infiltrated Atomic as a stripper and spied on Shaw's conversation with Hendry, thus learning of the existence of mutants.