Kohlar was a Klingon commander of a generational D7-class Klingon battle cruiser that ended up in the Delta Quadrant. Beginning with his great-grandfather, Kohlar was one of the four generations, of Klingons that were searching for the kuvah'magh, or savior.
Upon meeting B'Elanna Torres, who was pregnant, Kohlar, who felt that his crew had suffered long enough and should settle a planet somewhere, jumped on this fortunate coincidence and proclaimed that she was carrying the kuvah'magh. He destroyed his own ship so that he and his crew could stay aboard Voyager and witness the birth of their savior. He later admitted that he didn't know whether her child was their savior or not, but asked her to help him convince his people that it was.
Many of Kohlar's crew did not believe that Torres was carrying the kuvah'magh due to her half-Human heritage. A battle ultimately ensued for control of Voyager. After the crew of Voyager prevailed, the Klingons were cured of the deadly nehret by The Doctor synthesizing an antivirus from the fetus' hybrid stem cell antibodies. This convinced the rest of the Klingons that the prophecy had been fulfilled. They were later beamed down to a new planet that would become their home, with Kohlar giving his great-grandfather's antique bat'leth to Torres as a gift for the baby. (VOY: "Prophecy")