Note: X and Y are coordinates (light years on XY plane) relative to Terra at (0, 0)
Blantleff neighbouring systems
- 2596 - No record 
- 2750 - No record 
- 2764 - No record 
- 2765 - No record 
- 2822 - No record 
- 2930 - Lothian League 
- 2992 - Circinus Federation / Lothian League (simultaneous colonization)
- 3003 - Lothian League 
- 3025 - Lothian League 
- 3030 - Circinus Federation 
- 3040 - Circinus Federation 
- 3050 - Circinus Federation 
- 3052 - Circinus Federation 
- 3055 - Circinus Federation 
- 3057 - Circinus Federation 
- 3059 - Circinus Federation 
- 3063 - Circinus Federation 
- 3066 - Marian Hegemony 
- 3067 - Marian Hegemony 
- 3075 - Marian Hegemony 
- 3079 - Marian Hegemony 
- 3081 - Independent world 
- 3085 - Marian Hegemony 
- 3130 - Marian Hegemony 
- 3135 - Marian Hegemony 
- 3145 - Marian Hegemony 
Blantleff was settled in 2992 by settlers from both the Circinus Federation and the Lothian League. The colonies were small - a few hundred settlers from each nation, co-existing peacefully - and there is some evidence that the Lothians, who referred to the planet as Dersidatz, were unaware of the presence of the Circinians. The two groups were largely pastoral, herding animals and located hundreds of kilometers away from each other, and up until 3003 there were no problems between them.
In 3003, someone within the Circinian government decided that Blantleff should be a solely Circinian holding, and troops from the Federation attacked the Lothian settlements, determined to kill the Lothian colonists. Within the Lothian population was a man named Blantz, the only Lothian colonist with the benefit of a higher education, and fortunately for the Lothians Blantz was familiar with the history of Kentares IV and the massacre perpetrated there by the Draconis Combine. The nomadic Lothian population knew when to expect a DropShip to arrive, making a regularly scheduled supply run and collecting livestock for sale elsewhere; under Blantz's direction, the Lothians who survived the first raid sent out a distress call and then powered down all their equipment. Then, using Blantz's memory of the tactics used by the survivors on Kentares, the Lothian nomads survived by following behind the Circinian troops. By staying in the wake of the search parties but staying out of sight, the Lothians managed to survive until the supply DropShip arrived. Learning of the colonist's plight from the distress call, the DropShip was able to trace the call to the Circinian rear areas. Having not bothered to secure the area while they hunted, the Federation forces were surprised and decisively defeated by the Lothians.
Following this defeat in 3003, the Circinians abandoned Blantleff to the Lothians, and it would remain a Lothian possession for at least two decades without being contested by the Federation although by the time of the Clan Invasion Blantleff had been incorporated into the Federation.
Marian Hegemony Invasion
In January 3066 Blantleff was invaded by the Marian Hegemony, with VI Legio landing on the world as a part of the first wave of the invasion of the Circinus Federation led by Caesar Julius O'Reilly. Blantleff was captured within weeks, with the Marian invaders being greeted as liberators in many ways by the population of the planet.
VI Legio expected to act in support of the next stage of the invasion, but the Circanian President, H. R. "Little Bob" McIntyre had been aware of the likelihood of an invasion and had sought aid from neighbouring states. The assistance provided by the Magistracy of Canopus and the Rim Collection within the Free Worlds League was deliberately covert, and consisted of them hiring small mercenary concerns as proxies for the Federation. Some of those mercenaries were deployed to Blantleff, where they tied down the forces of VI Legio with repeated small-scale hit-and-run attacks. This was then followed up by an attack on VI Legio by forces disguised as reinforcements from IV Legio, but which were actually elements of the McIntyre House Guard and the Black Warriors, equipped with new BattleMechs provided by the Word of Blake. Although similar tactics had been used on Maximillian, the ruse had been discovered, and VI Legio counterattacked the infiltrators with surprising ferocity, despite the Legion being understrength at the time. The attack kept VI Legio out of the attempted conquest of Circinus itself, but within two weeks the Federation forces on Blantleff had been defeated; the invasion was subsequently halted by Caesar O'Reilly, but VI Legio rebuilt using the salvage from the Federation forces and remained in place on Blantleff in anticipation of Circanian attacks.
A task force of Word of Blake troops attacked Blantleff on the 18th of March 3070, striking at the Marian world from staging bases inside the Circinus Federation. Blantleff would be attacked again on the 17th of March 3075 when both Blantleff and Maximillian were attacked by forces of cybernetically-augmented troops from the Circinus Federation. Although the attackers were unable to conquer Blantleff or Maximillian, they did capture the nearby worlds of Khon Kaen and Poulsbo.
- VI Legio
- Secunda Cohors
- Tertia Cohors
| Systems within 60 light-years (distance in light years)|
Closest systems first:
|Maximillian||26.9||Thadora's Land||35.0||Zorn's Keep||38.9||Valerius||41.2|
|New St. Andrews||46.1||Sierra||56.5||Lordinax||57.2||Hardisey's Haven||58.2|
- Era Report: 3145, p. 38, "Inner Sphere Map - "
- Field Manual: 3145, p. VI, "Inner Sphere - 3145"
- The Periphery, 1st Edition, p. 65-66, "Tactical Developments"
- Historical: Reunification War, p. 158, "Inner Sphere -  Map"
- Era Report: 2750, p. 36, "Inner Sphere -  Map"
- Field Manual: SLDF, p. vii, "Inner Sphere -  Map"
- Historical: Liberation of Terra Volume 1, p. 10, "Inner Sphere -  Map"
- Field Report 2765: Periphery, p. 38, "Rim Worlds Army Deployment Map - "
- Historical: Liberation of Terra Volume 2, pp. 122-123, "Inner Sphere -  Map"
- Handbook: Major Periphery States, p. 163, "Marian Hegemony at various stages Founding (2930), Post Lothian Invasion (3055), Post Illyrian invasion (3063), Current (3067)"
- Handbook: House Steiner, p. 47, "Lyran Commonwealth after Third Succession War -  Map"
- Handbook: House Steiner, p. 56, "Lyran Commonwealth after Fourth Succession War -  Map"
- Historical: War of 3039, p. 132, "Inner Sphere -  Map"
- Handbook: House Steiner, p. 59, "Lyran Commonwealth after War of 3039 -  Map"
- Era Report: 3052, p. 10, "Inner Sphere -  Map"
- Era Report: 3052, p. 22, "Inner Sphere -  Map"
- Handbook: House Steiner, p. 61, "Lyran Commonwealth after Clan Invasion -  Map"
- Era Report: 3062, p. 10, Inner Sphere -  Map
- The Periphery, 2nd Edition, p. 110, "Rim Collection & Circinus Federation"
- Era Report: 3062, p. 28, "Inner Sphere -  Map"
- Inner Sphere (sourcebook), p. 98, "Near Periphery Kingdoms"
- Field Manual: Updates, p. 194-195, "Historical Brief"
- Handbook: Major Periphery States, p. 169, "Circinus Federation -  Map"
- ' Jihad: Final Reckoning, p. 42, "Inner Sphere -  Map
- Handbook: House Steiner, p. 70, "Lyran Commonwealth after FedCom Civil War -  Map"
- Jihad Secrets: The Blake Documents, p. 64, "Inner Sphere -  Map"
- Field Report: Periphery, p. 23, "Marian Hegemony Region Deployment Map - [August 3079]"
- Jihad: Final Reckoning, p. 62, "Inner Sphere Map - [March 3081]"
- Field Manual: 3085, p. 127, "Inner Sphere Map - [October 3085]"
- Map of the Inner Sphere 3130
- Era Report: 3145, p. 10, "Inner Sphere Map - "
- Field Manual: Updates, p. 195, "The Marian Legions"
- Field Manual: Updates, p. 197, "The Caesar's War"
- Jihad: Final Reckoning, p. 48, "The Jihad In Review"
- Jihad Hot Spots: Terra, p. 15, "Timeline of the Jihad"
- Jihad: Final Reckoning, p. 53, "The Jihad In Review"
- Field Manual: Updates, p. 202-203, "Marian Hegemony Armed Forces"
- Mercenaries Supplemental, p. 69, "Mercenary Employment Table"
- Era Report: 2750
- Era Report: 3052
- Era Report: 3062
- Era Report: 3145
- Field Manual: 3085
- Field Manual: 3145
- Field Manual: SLDF
- Field Manual: Updates
- Field Report 2765: Periphery
- Field Report: Periphery
- Handbook: House Steiner
- Historical: Liberation of Terra Volume 1
- Historical: Liberation of Terra Volume 2
- Historical: Reunification War
- Historical: War of 3039
- Inner Sphere (sourcebook)
- Jihad: Final Reckoning
- Jihad Hot Spots: Terra
- Jihad Secrets: The Blake Documents
- Map of the Inner Sphere 3130
- Mercenaries Supplemental
- The Periphery, 1st Edition
- The Periphery, 2nd Edition