According to the script for the Star Trek: The Next Generation third season episode "Yesterday's Enterprise", Archduke Ferdinand was a Human who was assassinated in Sarajevo.
In an alternate timeline, in which the Federation was at war with the Klingon Empire, Captain Jean-Luc Picard and Guinan debated the merits of returning the USS Enterprise-C to its time period. If the Enterprise-C was returned, Guinan believed that history would readjust itself. When arguing against readjusting history in an effort to prevent lives that might be lost in a war, Picard gave this example as one where preventing an action from happening would prevent a war and the subsequent loss of life. The line in which Archduke Ferdinand was mentioned did not make it into the final episode.