|Part of Second Succession War|
|Commanders and leaders|
|Coordinator Miyogi Kurita||First Prince Michael Davion||Triumvirate Regency|
The Marathon Offensive was mounted by the Draconis Combine during the Second Succession War against its neighboring Successor States, the Federated Suns and the Lyran Commonwealth. Over a four-year period the Combine made only limited territorial gains from the Lyrans but managed to conquer Robinson, capital of the Suns' Draconis March.
Despite suffering a narrow defeat at Hesperus II in 2853, Coordinator Miyogi Kurita felt that the Commonwealth - with its Triumvirate Regency mired in internal problems - was vulnerable to a new and broader offensive. With strife between the unpopular First Prince Michael Davion and his subjects also plaguing the Federated Suns, Miyogi planned attacks against that realm too. Discarding his predecessors' planet-hopping strategy, Miyogi ordered his generals to instead mount strong and deep incursions intended to secure large swathes of territory. 
The Marathon Offensive
Federated Suns Front
In April 2854 the DCMS opened its offensive against the Federated Suns with a raid-in-force against Kentares IV. Over the next six weeks the AFFS defenders waged a hit-and-run campaign against the invaders, with both sides sending reinforcements to the contested planet. However, this assault was in fact a diversion - with the infamous Kentares Massacre on the Suns' mind, the DCMS correctly expected its opponents to shift strength away from the real target: Robinson.
The main offensive commenced in June with all-out attacks on Lucerne and Franklin, with a second wave hitting Rochester, Le Blanc and Robinson in July. Despite stiff resistance from the AFFS all but Le Blanc and Robinson had fallen to the Combine by mid-2855. Le Blanc's defenders eventually drove the invaders off-world. Despite being strongly protected the capital of the Draconis March, on the other hand, ultimately could not hold out against the four Sword of Light regiments and ten supporting regiments. Led by Miyogi Kurita personally, the Combine forces used all types of weapons of mass destruction to break AFFS resistance, a battle that became known as the "Rape of Robinson". Unable to divert reinforcements from Kentares, Prince Davion decided that the morale blow from surrendering Robinson was less costly than continued fighting and ordered AFFS units to retreat in August 2858.
Elsewhere the offensive proceeded less successfully for the Combine. Attacks throughout 2855 and 2856 failed to conquer any of the targeted worlds, and the quagmire on Kentares finally ended in AFFS victory in July 2856. With its troops thus released for duty elsewhere, the Suns was able to blunt further Combine incursions and reclaim Benet III and Cassias in 2857.
Lyran Commonwealth Front
In contrast to the more narrowly focused assault on the Federated Suns, the attacks against the Lyran Commonwealth were staged all over the border from the coreward Tamar Pact to Isle of Skye worlds near Terra. While the LCAF was able to fight off the invaders on several planets, the Combine was swift to exploit any weaknesses discovered and by the end of 2857 a dozen Lyran worlds had fallen to the Dragon, most notably a salient stretching from Rubigen to Orestes. Lyran counterstrikes proved unsuccessful in reclaiming the lost territory (except for Kelenfold), though the DCMS paid heavily in defending its gains. Elsewhere, however, another Lyran offensive rimward of Orestes recaptured worlds lost to the Combine during the previous war. In the end, the Combine was left with a gain of only six worlds on the Lyran front when Miyogi called off the Marathon Offensive in December 2858.
The Marathon Offensive officially ended in 2858, although fighting and territorial changes continued for some years after. While the Combine-Lyran border had only somewhat changed in the Combine's favor, the conquest of Robinson was a triumph that stung the Federated Suns' pride and would stand for a generation until well into the Third Succession War. Even though the Combine military suffered from supply shortages as a result of the Marathon Offensive, its victories allowed Miyogi Kurita and the Combine to end the Second Succession War as arguably one of its winners.