Word of Blake was once part of ComStar, part of the fictional BattleTech universe, but splintered from the order due to a difference in beliefs. It was founded by Demona Aziz, then Precentor of Atreus. Created after the death of Primus Myndo Waterly and the Battle of Tukkayid that halted the Clan invasion, it at first received support and refuge from the Free Worlds League, who employed them to control their hyperpulse communications network. However, it eventually captured Terra from ComStar in 3058. Ultimately, after the FedCom Civil War that ended in 3067, the Word of Blake launched a jihad against the rest of the Inner Sphere.
The opening of the Jihad included an attack by allegedly rogue mercenary units on the Wolf's Dragoons homeworld of Outreach as well as assaults on Tharkad, New Avalon, Luthien and several other important worlds. The goal of the Word of Blake Jihad was an extension of the original plans of ComStar's founder Jerome Blake, called Operation Silver Shield, to capture some of the Terran Hegemony worlds and hold them under ComStar's control.
However, resistance began to grow when Professor David Lear and the Republic of the Sphere's future founder, Devlin Stone, escaped from a Word of Blake reeducation camp and organized a local resistance movement that destroyed Word of Blake forces on the world of Kittery. Soon, the resistance developed into a widespread organization that was joined by ComStar, the Successor States, the Clans, and the mercenary unit Wolf's Dragoons, and, thence united, succeeding in pushing the Word of Blake back until their final defeat on Terra in 3081.
During the fourteen year Jihad, Word of Blake forces used weapons of mass destruction on military and civilian targets alike. Most Inner Sphere worlds were struck with nuclear and/or biological weapons on some scale. Some worlds, such as New Earth, were nuked repeatedly, making them sterile and uninhabitable. This led in part to the absolute lack of mercy shown by Devlin Stone's forces when facing the Jihadists in combat.