The Rangers are an elite interstellar military force featured on the television show Babylon 5.
Who Are the Anla'Shok?
We first encounter the Rangers in episode 9 of season 2, "The Coming of Shadows." They are a joint Human/Minbari secret military force that is highly trained in military tactics, meditation, and both armed and unarmed combat. They are trained primarily on the Minbari homeworld, although they do have other training centers, such as a facility on a Drazi colony world. Their main mission, inititally, is to roam the frontiers and report back any information that is too sensitive for normal channels of communication.
In Minbari, the Rangers are called Anla'Shok. In English, their leader is called Ranger One, which in Minbari translates to Anla'Shok Na or Entil'Zha. The first leader of the rangers was Valen, who formed them 1,000 years ago. They were a Minbari-only organization until 2259 when their ranks were opened to humans and following the formation of the Interstellar Alliance other races such as the Pak'ma'ra and Drazi were also encouraged to join.
The Changing Role of the Rangers
The Rangers began as a secret spy force for the Minbari. However, during the Shadow War in 2260 they became an active military force used to fight the Shadows and eventually the Vorlon Empire. They accomplished an incredible amount of success mostly due to their cutting edge starships: The White Stars. The White Stars were a semi-organic Minbari/Vorlan joint project and thus they were among the fastest and, for their size, most powerful starships of the time, fully capable of taking on a properly subdued Shadow vessel.
After the end of the Shadow War, the Rangers and the White Stars, then under the leadership of Delenn and John Sheridan, assisted in the military assault on Earth to overthrow the global dictatorship then controlling Earthgov. This was spearheaded by Sheridan and his renegade forces on Babylon 5, relying heavily on the White Star ships for support.
Following the retaking of Earth, the White Stars and the Rangers moved to a support role for the newly formed Interstellar Alliance. During peacetime, they patrolled the borders of member worlds' space, protecting them from raiders and general spacefaring ne'er-do-wells. During times of conflict, the White Star fleet gave the Alliance the power it needed to enact its decisions and be more than just a figurehead organization. The ships and the Rangers on board enforced embargoes, carried out dangerous tactical surveillance, and engaged in outright military action when necessary.
Also hinted at, although never fully explored in the series, is the role of the Rangers in the far future. We do know (thanks to "The Deconstruction of Falling Stars," the last episode of season four) that about 500 years in the future, Earth will go through The Great Burn, probably some sort of nuclear holocaust. After this time, the Rangers will operate on Earth in secret, working to preserve and rediscover lost scientific knowledge.
Shining Stars of the Rangers
The most important Rangers on Babylon 5 were Marcus Cole and Lennier. Marcus was on the show from seasons 2 through 4. He was a good natured, jovial Brit who also happened to have major issues from his past and an impressively doomed star crossed love going for Commander Susan Ivanova. Lennier was the diplomatic attaché for Ambassador Delenn, joining the Rangers in the fifth season in a misguided attempt to work out his undying love for Delenn.
Both of the characters' time as Rangers brought out great depth in their characters, bringing to the forefront the question: what are you willing to give up your life for?
We Live for the One, We Die for the One
The Rangers are an expert military force that plays a vital role in the events in Babylon 5. Without their ships and fighting abilities, the forces of light would be left high and dry with lots of ideals and nothing to back it up. They are what give the resistance on Babylon 5 and the later Interstellar Alliance the power to be a political force. The Rangers, to the last, have all dedicated their lives and deaths to working to further peace and understanding in the galaxy.