Tensions increased between the Earps and both the Clantons and McLaurys through 1881. Three cowboys attempted to rob a Kinnear & Company stagecoach on March 15, 1881, at 10 pm, which was reportedly carrying $26,000 in silver bullion (about $ in today's dollars). The amount of bullion which the stagecoach actually carried is questioned by modern researchers, who note that the bullion would have weighed about , since the value of silver at the time was $1 an ounce—a significant weight for a team of horses. According to Wells Fargo agent John Q. Jackson, a stagecoach typically carried an Express Box containing bullion weighing only .