In2261,theVorlonsjointheShadowWar,buttheirtacticsbecomeaconcernforthealliancewhentheVorlonsbegindestroyingentireplanetswhichtheydeemtohavebeen"influenced"bytheShadowsDisturbedbythisturnofevents,Babylon5recruitsseveralotherpowerfulandancientracestheFirstOnestotheircause,againstboththeShadowsandtheVorlonsCaptainJohnSheridanreturnstothestationafterescapingfromZ'ha'dum,butataprice:barringillnessorinjury,hehasonly20yearslefttoliveHeisaccompaniedbyamysteriousaliennamedLorienwhoclaimstobetheoldestsentientbeinginthegalaxy
HoursbeforeSheridan'sreturn,Garibaldiisrescuedandreturnedtothestation,inratherdubiouscircumstancesHeismarkedlymoreparanoidandsuspiciousofotheralienracesandofSheridanthanhewasbefore
CentauriEmperorCartagiaforgesarelationshipwiththeShadowsLondoMollariengineerstheassassinationofCartagiaandrepudiateshisagreementwiththeShadowsLondokillsMrMordenanddestroystheShadowvesselsbasedontheCentaurihomeworld,inanattempttosavehisplanetfromdestructionbytheVorlonsAidedbytheotherancientraces,andseveralyoungerones,SheridanluresboththeVorlonsandtheShadowsintoanimmensebattle,duringwhichtheVorlonsandShadowsrevealthattheyhavebeenleftasguardiansoftheyoungerraces,butduetophilosophicaldifferences,endedupusingthemaspawnsintheirendlesswarsthroughouttheagesTheyoungerracesrejecttheircontinuedinterference,andtheVorlonsandShadows,alongwiththeremainingFirstOnes,agreetodepartthegalaxyforever
AftertheShadowsaredefeatedGaribaldileaveshispostassecuritychiefandworksonhisownasa"providerofinformation"HebeginsworkingforoneWilliamEdgars,aMarsTycoon,whoismarriedtoGaribaldi'sformerloveWhileheworksevercloserwithEdgars,hebecomesincreasinglyaggressivetowardsSheridanandeventuallyleavesBabylon5
MinbarisgrippedbyabriefcivilwarbetweentheWarriorandReligiouscastesDelennsecretlymeetswithNeroonoftheWarriorcasteandconvinceshimthatneithersidecanbeallowedtowinShetellshimthatshewillundergoaritualwhereinshewillbewillingtosacrificeherself,butwillstoptheritualbeforesheactuallydiesWhenNeroonseesthatsheactuallyintendstogothroughtheentireritual,herescuesherandsacrificeshimselfinstead,declaringthat,althoughhewasbornWarrior,inhisheartheisReligious
AspartoftheongoingconflictbetweenEarthandBabylon5,GaribaldieventuallybetraysSheridanandarrangeshiscaptureinordertogainEdgars'trustandlearnhisplansGaribaldilaterlearnsthatEdgarscreatedavirusthatisdangeroustoonlytelepathsItisthenrevealed,thatGaribaldiwasactuallyabductedbythePsiCorpsattheendofSeason3andreprogrammedbyBestertoprovideinformationtohimattherighttimeBesterreleasesGaribaldiofhisprogramming,andallowshimtoremembereverythinghehasdonesincebeingkidnappedEdgarsiskilledandhiswifedisappears,butisreunitedwithGaribaldiaftertheendofthewarGaribaldihelpsfreeSheridanandreturnhimtothecampaigntofreeEarthAnallianceledbyBabylon5freesEarthfromtotalitarianrulebyPresidentClarkinashortbutbloodywarThisculminatesinClark'ssuicideandtherestorationofdemocraticgovernmentMarsisgrantedfullindependence,andSheridanagreestoresignhiscommissionTheLeagueofNonAlignedWorldsisdissolvedandreformedintotheInterstellarAlliance,withSheridanelectedasitsfirstPresidentandcontinuinghiscommandoftheRangers,whoaretoactasagalacticequivalentofUnitedNationspeacekeepers
Intheseasonfinale,theeventsof100,500,1000,andonemillionyearsintothefutureareshown,depictingBabylon5'slastinginfluencethroughouthistoryAmongsttheeventsshownarethepoliticalaftermathofthe2261civilwar,asubsequentnuclearwaronEarthinvolvinganewtotalitariangovernmentintheyearAD2762,theresultingfallofEarthintoapreindustrialsociety,thelossandrestorationofhumanity'sknowledgeofspacetravel,andthefinalevolutionofmankindintoenergybeingssimilartotheVorlons,afterwhichEarth'ssungoesnova
