Hiromi Takeshewada served aboard the Mandela as an ensign, sometime prior to the mid-2260s. The Mandela was destroyed less than a month after she had transferred off the ship. (TOS - The Brave and the Bold, Book One novella: The First Artifact) There is little data to establish the dates of the Mandela's operation or destruction, except that Takeshewada held the rank of commander by 2266.