The Battle of Medina Station was a major battle of the Free Navy Conflict that took place in the Slow Zone in which the Consolidated Fleet fought the Free Navy for control of the station. The battle ultimately ended with the Rocinante defeating all Free Navy members and forcing their surrender, thus enabling the UN, MCR and OPA to assume control of the station.
After Michio Pa's group seceded from the Free Navy, it was possible for them to accede to the Consolidated Fleet, comprised of the UN, MCR and OPA. However, while traveling towards the meeting location, Fred Johnson, the de facto leader of the OPA, has a stroke and dies while in battle with Marco's Pella and two other Free Navy ships.
After Johnson's death, Holden and co. convince the Consolidated Fleet to gather forces and make coordinated attacks on the Free Navy's holdings, as means to counteract the organization and liberate the Sol system from its grip. The Allies agree, and decide to send the Rocinante and the Giambattista a water hauler to re-take the Medina Station.
The Rocinante and the Giambattista, which is filled with almost four thousand small rocket-driven ships and missiles, make a hard burn for the Sol Ring Gate in order to take down the railgun defenses installed by the Free Navy on the Medina Station in the Slow Zone.
Before entering the ring two Free Navy ships catch Rocinante and the Giambattista however were travelling at over 8G and were only in range for seconds and would take several hours to return. The ships were only minimally damaged and the Giambattista fired its first wave of missiles and rockets through the ring.
With the diversion in place, the OPA forces, Bobbie and Amos make a dive for the railgun defenses. Bobbie finds the railguns protected by a small force comprised of Duarte's Martians. Bobby eventually disables the railguns by destroying the fusion core powering them all.
After the defenses installed by the Free Navy are destroyed, Holden's crew and the OPA proceed in fighting Duarte's men, which results in all of its occupants surrendering. Holden then takes command of the station, officially ending the FN occupation.
Having doubled back one of the Free Navy ships that had briefly engaged the Rocinante and the Giambattista entered through the Sol gate, but was immediated destroyed by a railgun hit from Rocinante ending the engagement.
Following the liberation of the Medina Station, the Free Navy's grip was weakened even further. As one last attempt to retake the station, the Free Navy sends the rest of its forces on a hard burn to the gate to overwhelm the small OPA force and the Rocinante, which were present there.
Understanding that winning the battle outright is impossible, Naomi uncovers the mechanism which resulted in certain previous ships disappearing after attempting travel through the Ring network: a very large ship, as well as heavy traffic, can overwhelm the wormhole's physical capabilities, resulting in the ships forever being stranded in its throat.
Using the recent revelation, Naomi overloads the Sol Ring's capabilities at the time the Free Navy was attempting travel through the Gate. Much like the Barkeith, Marco's Free Navy remains stranded in higher space-time.