In Arthur, we actually meet the Earth Force gunner who started the Earth/Minbari War. He was the man who, without orders, opened fire on the Minbari Leader, Dukhat's flagship. As Arthur, he headed to downbelow to roam and finds an old lady who is lying in her little alcove crying. She tells him why (some thieves stole her ramaining belongings, including a picture and frame, the only item she had to remember her late husband with) and sets out to find the thieves. After defeating the thieves, they refused to "submit" and warned Arthur that they "have friends". To Arthur's surprise, G'Kar was the only one who was honorable enough to stand at his side. For that, Aurthur "Knighted" G.Kar, dubbing him "Sir G'Kar, the Red Knight".
The person that would eventually find this out would be Dr. Franklin, thanks to a DNA scan. Captain Sheridan also tries to convince the League Of Non-Alligned Worlds to sign the "Babylon Treaty" in which each world representative that signs agrees they won't start any wars against any other race that signs the treaty.