In the wake of the disastrous Operation Scorpion and Reformation and Secularization of the Order, the former ComStar split into the secular non-religious ComStar and the fanatical off-shoot the Word of Blake. ComStar held the bulk of the original Order's Hyperpulse Generator stations as well as its headquarters world of Terra, while the Word sought exile in Free Worlds League under former ComStar Adept Captain-General Thomas Marik.
The Blakists however only considered the League a temporary home, openly desiring to unseat those they derided as Heretics from Humanity's homeworld, despite the fact the secular ComStar had a considerable military advantage, with even the heavily damaged post-Battle of Tukayyid Com Guards numbering some 50 Divisions to the newborn Blake Guards meager five. The Blakists thus turned to their one area of superiority to ComStar, covert intelligence. With over two-thirds of the pre-Schism ROM defecting to the Word, Precentor ROM Alexander Kernoff set about purging ComStar infiltrators as well as sneaking agents back into the secular Order, leaving it all but blind to the Word's intentions and preparations for a future strike.
The Word of Blake's efforts received a considerable boost with the Marik/Liao invasion of 3057, placing the regained Free Worlds League and Capellan Confederation worlds' HPG stations in Word of Blake hands as well opening opportunities to secure many more in the politically unstable region near Terra called the Chaos March. The Blakists' increasing control of communications in the region and the spike in troop movements allowed them to shift their forces closer to Terra underneath the secular ComStar's nose, with the Word agents within the secular ROM suppressing what little information did reach them.
The political instability of the Chaos March also resulted in a huge demand for mercenary units, enticing many units to seek new contracts, including the ComStar-employed Brion's Legion. Contracted with the Order since their disastrous showing in the Fourth Succession War, the chance for a short-term high paying contract and finally emerging from ComStar's shadow prompted the Legion to leave Terra. With the Legion making up half of the depleted post-Tukayyid Com Guards Terran Defense Force, ComStar was left with two choices, hire another mercenary unit or reassign a Com Guard division deployed elsewhere in the Inner Sphere.
ComStar initially favored shifting one of the divisions formerly located in the disputed Lyons Thumb that had been transferred to bolster the defenses in the Free Rasalhague Republic in the wake of the Refusal War, but fearful of inflaming tensions with Archon Katherine Steiner-Davion and Precentor Martial Anastasius Focht's caution against any weakening of the Com Guard forces along the Clan Border resulted in the fateful decision to replace the Legion with another mercenary unit. Among the short-list of suitable replacements for the Legion was the highly regarded 21st Centauri Lancers.  
The Shadow Lancers
Formerly employed by the Free Worlds League,the Lancers were one of the mercenary units used by Thomas Marik to recapture Sarna March worlds, bolstering the Marik forces landing on Wasat. Unfortunately the Captain-General would then "loan" the Lancers to the Capellan Confederation, the unit taking heavy causalities aiding McCarron's Armored Cavalry against the Second FedCom RCT on Hsien. Aggrieved at the poor treatment by Thomas Marik, the Lancers terminated their almost forty year contract with the Free Worlds League, with Colonel Evelena Haskell using a Word of Blake HPG station to send notification to Outreach that her mercenary unit was for hire.
With word of this reaching the Word of Blake's ad-hoc leader Precentor William Blane in the wake of learning of ComStar's search for a replacement for Brion's Legion, Blane sensed a unique opportunity and hurriedly travelled with the Blakist Precentor Martial Trent Arian to Atreus. Seeking an audience with Captain-General Thomas Marik, Blane and Arian presented their plan to induce ComStar to hire the Lancers as replacements for Brion's Legion, secretly substituting disguised Word of Blake troops for the mercenaries, severely weakening ComStar's Terran Defense Force to pave the way for a successful invasion. While declining to provide direct military aid, the Captain-General did agree to provide logistical and transport assets as well as ordering the League's military and intelligence agencies not to interfere.
Returning to Gibson by means of a League provided Command Circuit, Blane and Arian met with the Blakists' Ruling Conclave and rapidly secured support for the plan, now code-named Operation Odysseus. By this time ComStar had also narrowed their list of suitable replacements for the Legion, with the highly respected 21st Centauri Lancer's A-rating and subtle maneuvering by Blakist elements within the secular Order prompting ComStar to sign a five-year contract with the mercenary unit on November 30th 3057, with the Lancers to arrive on Terra by January 3058.
With the first phase of Operation Odysseus complete, elements of the 6th and 1st Division then assaulted Nestor, the home base of the Lancers and took the unit's dependents to Gibson as hostages. When the real Lancers arrived on Nestor, the 1st Division's commander Precentor Suzanne Mulvanery offered them a stark choice, lay low for the next few months and be reunited with their families or put their dependents' lives at risk if they chose to oppose the Word. The mercenaries reluctantly complied. The two Word of Blake divisions then proceeded to reorganize themselves to match the reported composition of the real 21st Centauri Lancers while Blakist operatives within ComStar altered Com Guard records to avoid security problems with the Lancers' "new personnel recruited to replace losses on Hsien". The new "Shadow Lancers", led by Mulvaney masquerading as Colonel Evelema Haskell, headed to Terra.
Landing in January in the midst of regular Com Guard rotation of troops with the 104th Division shifted to the Free Rasalhague Republic and with Precentor Martial Focht hosting interstate wargames on Tukayyid, the so-called Shadow Lancers immediately occupied the facility recently vacated by Brion's Legion at Bowling Green. Kentucky. Within days the disguised Word of Blake units began a series of joint orientation exercises with the Com Guard 201st Division's Alpha and Beta Battalions, slowly reaching out to Word of Blake sympathizers and agents within ComStar. With Precentor Martial Focht and the Com Guard high command distracted by the Battle of Coventry and paying scant attention to Terra's military defenses, by the end of February the Shadow Lancers were in place and ready to launch their attack. Luck also continued to favor the Blakists when a spate of bad weather flared up across North America and confined many Com Guard units to base, prompting the Word's forces to strike.  
On Febuary 28 as the TDF's new commander Precentor Lisa Koenigs-Cober's DropShip approached Bowling Green for an inspection tour of the 21st Centauri Lancers, a pair of Shadow Lancer fighters shot her ship down in Odysseus's opening move. Simultaneous to this strike, Word of Blake agents began operations across Terra, the single most effective one being computer-systems engineer Satoshi Fujishima. Posing as a civilian computer systems engineer, Fujishima had been hired during ComStar's overhaul of their computerized base security in the wake of the Schism, installing a "backdoor" that gave him almost complete control over ComStar's computer systems. When the Shadow Lancers attacked Koenigs-Cober's DropShip, Fujishima sent a command sequence to all Com Guard and TerraSec facilities that they were overrun by enemy forces and to go into autonomous mode, the defense systems assuming the ComStar personnel inside were hostile and trapping them within their own bases. As a result, Fujishima had effectively neutralized some 200 Com Guard and TerraSec bases, greatly simplifying the Blakist offensive.
The next step, the capture of Hilton Head complex, however did not go according to plan. While the lockdown left Hilton Head's security in shambles and prevented its personnel from broadcasting requests for help, the Primus's bodyguard unit of light armor and infantry put up stiffer than expected resistance to the Shadow Lancers' armor forces charged with taking the complex, the Blakist forces pulling back to soften it up with artillery fire in preparation for a second assault.   Elsewhere Blakist moles assassinated key ComStar officials and attacked important Com Guard barracks and armories, including a nerve gas attack to neutralize ComStar ROM's headquarters near Cairo, preventing a unified effect defense against Odysseus.
With the 201st Division serving as the main security force for North America, the Shadow Lancers targeted their base at Salina, Kansas as a priority target once the Blakists launched their assault against Hilton Head. Despite their numerical superiority, the Precentor Mulvanery opted for a surprise attack, with a pair of Lancer fighters requesting emergency landing clearance before dropping two J91 Fuel-Air Explosive devices on the base, destroying the 201st's command staff and killing or injuring almost half its combat-ready troops. However the unit's junior officers under Adept Edelle Kearny rallied the survivors of the 201st against the Blakists, the remaining 22 BattleMechs of the 201st withdrawing under the cover of a raging blizzard, breaking free of the encircling Blakist forces to head toward the Gunnison Castle Brian in the Rocky Mountains.  
Coinciding with Blakist WarShips staging disruption raids against the Com Guard fleet bases at Luyten 68-28 at Ross 248, by the last hours of Feburary 28th the Word of Blake's invasion flotilla began to arrive via a Pirate Jump Point in trans-lunar orbit. Unable to call upon WarShip reinforcements, the Com Guards forces on Luna were unable to prevent the Word of Blake fleet reaching Terran orbit.
With the scattered SDS stations presenting a deadly threat to the Word's invasion and not effected by the Com Guards general computer systems lockout, as the Blakists fleet approached Terra, the Word launched commando raids to seize control of them. While the majority easily fell to the Word's Tornado-equipped troops, others put up more resistance such as the Santo Tomas Andean laser battery which was able to launch its Damocles mirror to orbit before it finally fell.   
With imminent Blakist reinforcements, the Shadow Lancer armor surrounding Hilton Head began to advance into complex. Unfortunately TDF commander Lisa Koenigs-Cober and a fellow MechWarrior who had both survived the initial strike against her DropShip unexpectedly arrived and disrupted the Shadow Lancer troops, allowing the ComStar forces to evacuate the Primus and remove or destroy vital equipment.   By midday the Blakist forces arrived and began to land troops at primary and secondary sites across Terra, a regiment sized formation at Com Guards Terran based headquarters at the Sandhurst Royal Military College in the British Isles with two Level III's each assigned to take the Terran Government at Geneva and the Court of the Star League in Washington state.
Secondary forces of varying sizes and compositions landed at Ecole Militaire in Paris, key manufacturing and research facilities, the already pacified ROM headquarters near Cairo and several Com Guards facilities that escaped the lockdown such as the T'enchen Castle Brian in China. With Shadow Lancer 'Mech reinforcement, the Blakists finally took Hilton Head, though Com Guard booby traps inflicted heavy losses and crippled many of the facilities the Shadow Lancers hoped to take intact.  By the evening of the March 1st the Blakist Precentor Martial Trent Arian landed at Sandhurst to establish his command post, declaring martial law and requesting the Com Guard forces surrender, to which he received no replies. 
Battles elsewhere in the Terran System
Though focusing the bulk of their attention on taking Terra, the Word of Blake also launched attacks against the other notable ComStar held bases on Venus, Luna, Mars and the vitally important Titan Yards.
While the capture of Venus and the Military Academy of Aphros were easily achieved, one of the most dangerous attacks during Odysseus was the Blakist assault against the newly reopened War Academy of Mars. While Star League era terraforming provided the planet with a breathable atmosphere, the Word's 5th Division was ill-prepared for combat in Mars' lighter gravity, taking heavy losses against the WAM's cadets who were more experienced with the operations on world. Though the 5th was ultimately successful in taking the academy, only six Blakist BattleMechs were left operational at its conclusion, a narrow victory that could have easily gone either way.  
The battle for the Titan Yards was not so close. Having lost the element of surprise that allowed the attacks on Terra to succeed, the ComStar defenders were well prepared when the Blakist Liberation Fleet led by Gregory Zwick arrived. The heavier fighter screens of the Com Guard defenders easily repulsed the lighter Blakist fighters, inflicting heavy damage on the advancing Blakist fleet. While Zwick's forces succeeded in landing troops on a number of shipyards, the ComStar fighters aided by supporting DCMS ships being refitted at Titan as part of the Explorer Corps agreement soon forced Zwick to order a withdrawal, Com Guard forces quickly recapturing the Blakist held facilities. The arrival of a Com Guard Dante-class WarShip shortly after the battle's conclusion firmly cemented ComStar's control of the valuable facility.  
Fall of the Com Guard Defenders
Meanwhile in North America, the remnants of 201st's Alpha and Beta IV's fought a number of rear guard actions at Sharon Springs, Ordway and Pueblo as the Shadow Lancers pursued them,  until their luck ran out by March 2nd. Harried by the Blakist forces through the Front Range, the 201st's survivors succeeded in reaching the Gunnison Castle Brian only to discover they could not enter, having been under attack and unaware of the Blakist computer lock-down of Com Guard facilities. Trapped in a box canyon, the 201st found themselves caught between the Shadow Lancers and Blakist reinforcements moving down from Washington state. While a number of Com Guard 'Mechs were able to flee, the bulk were destroyed, with the 201st effectively ceasing to exist as a unit, signalling the end of the Com Guards' battle for North America.   
In the British Isles, the cadet forces at Sandhurst were somewhat luckier. When they proved unable to hold Sandhurst,  the cadets withdrew westward and divided into two, one group (Task Force Epee) heading toward the Salisbury Plain training ranges in the north, the others moving to secure supplies (Task Force Saber) and a route into Wales (Task Force Foil) in the south. While the northern group successfully used the training field's simulator and drone systems to confuse the attackers,  the southern groups fought a number of rearguard actions while gathering supplies through the Cotswold and Malvern Hills before heading towards the Severn River.   
Forced to use the two bridges just north of Bristol, while the bulk of the southern groups succeeded in crossing before Word of Blake fighters destroyed the main spans of each bride, over 20% of the Sandhurst cadets were trapped between the river and the invaders and forced to surrender.  The surviving task forces linked up and squared off with the numerically superior invaders in West Wales, both sides suffering heavy losses before the Com Guard forces finally crumbled, a few cadets escaping into the mountains before the remaining troops chose surrender over certain annihilation, signalling the end of active ComStar defense by March 5th.  
With the formal cession of hostilities on March 7th 3058, save for the Titan Yards the entire Terran system was under Word of Blake control.
Mistakenly assuming that both sides would want him alive to break the lockout and thus relatively safe, Satoshi Fujishima emerged from hiding on March 7th and made his way to Blakist occupied ComStar compound overlooking the Imperial Palace, only to be killed by a sniper within sight of its gate. While no-one claimed responsibility, it was assumed Fujishima was assassinated on the orders of the secular ComStar, because without his aid the Word found themselves the victim of their own strategy, forced to crack each Castle Brian and base manually, delaying their pacification.
While the Free Worlds League and Capellan Confederation immediately recognized the Word of Blake as the legitimate ruler of Terra, the Federated Commonwealth, Draconis Combine, Lyran Alliance and St. Ives Compact only grudgingly recognized the Word of Blake's de facto possession and agreed not to launch military action against Terra. The Free Rashalague Republic understandably joined with the secular ComStar in condemning the occupation, though ComStar indicated it would continue to focus the threat of the Clans in the immediate future. The Word's efforts to seek a seat on the Mercenary Review and Bonding Commission on Outreach were outright denied, while the Word did eventually release the 21st Centauri Lancers' families unharmed as they had promised, the betrayal and blackmail of the Lancers soured the Blakists' efforts to attract more reputable mercenaries.
By April 3058 Precentor Martial Trent Arian was named as Governor of Terra, the selection of the "officer on the ground" a compromise prompted by the increased political infighting among the Word of Blake in the wake of Odysseus. On Arian's instructions many of the reforms imposed by the secular ComStar were wound back as the Word shifted the bulk of their personnel to Terra.  
Rebuilding their forces using salvage and material looted from Com Guard storehouses, the Word faced resistance from guerrillas on all three of the Sol system's inhabited worlds.
- Shattered Sphere, p. 100 "The Fall of Terra - Opening Moves"
- The Fall of Terra, p. 7 "Operation Odysseus - Gathering Storm"
- Shattered Sphere, p. 100 "The Fall of Terra - The Shadow Lancers"
- The Fall of Terra, p. 8 "Operation Odysseus - A Wolf in Sheep's Clothing"
- The Fall of Terra, pp. 12-13 "Scenario 1: Hold the Line"
- Shattered Sphere, p. 102 "The Fall of Terra - Assault on Hilton Head"
- The Fall of Terra, p. 9 "Operation Odysseus - Homecoming"
- The Fall of Terra, pp. 14-15 "Scenario 2: When the Bough Breaks"
- Shattered Sphere, pp. 100-102 "The Fall of Terra - Outbreak of War"
- The Fall of Terra, pp. 16-18 "Scenario 3: Free Fall"
- Shattered Sphere, p. 102 "The Fall of Terra - War in Space"
- The Fall of Terra, p. 10 "Operation Odysseus - Capricious Fate"
- The Fall of Terra, pp. 45-46 "Scenario 14: God of War"
- The Fall of Terra, pp. 47-49 "Scenario 15: Per Ardua Ad Astra"
- The Fall of Terra, pp. 23-24 "Scenario 6: Nowhere to Run"
- The Fall of Terra, p. 10 "Operation Odysseus - The Tide Turns?"
- The Fall of Terra, pp. 50-51 "Scenario 16: End of the Line"
- The Fall of Terra, pp. 27-28 "Scenario 8: Serve to Lead"
- The Fall of Terra, pp. 34-35 "Scenario 9: Fields of Camlann"
- The Fall of Terra, pp. 36-37 "Scenario 10: Who Dares Wins"
- The Fall of Terra, p. 30 "Scenarios 9-12: Mini-Campaign Rules"
- The Fall of Terra, pp. 38-39 "Scenario 11: Croeso Y Cymru"
- The Fall of Terra, pp. 40-42 "Scenario 12: Season's End"
- The Fall of Terra, p. 11 "Operation Odysseus - New Order"
- Shattered Sphere, p. 102 "The Fall of Terra - Aftermath"