A former friend of Nero's and a key figure in the Roman political elite, Otho apparently fell from disgrace when he became involved with a woman desired by Nero himself. In order to remove his competition, Nero simply exiled him to faraway Portugal under the guise of a "promotion". Some ten years later after Nero's own ill-fated end, Otho hoped to return to Rome as Caesar under Galba who had gathered an army and prepared to claim the crown. Galba had had a politically favorable relationship with Otho and it's conceivable that the two could have had such an agreement. On becoming Augustus, however, Galba for whatever reason sidestepped Otho and named Piso Licianus, a garden variety aristocrat, as his successor. Infuriated at hearing the news of this betrayal, Otho summoned a sympathetic army and within days had Galba executed and placed himself as emperor.
Otho still had to deal with the approaching army of Vitellius who were already enroute to fight Galba. Although he set out with an able army to meet Vitellius's forces an unexpected turn of events had Otho commit suicide just prior to a major engagement. He did this, apparently, out of a patriotic need to end the civil war.
RIC 4, BMC 3 AR Denarius Obv: IMPMOTHOCAESARAVGTRP - Bare head right.
Rev: PAXORBISTERRARVM - Pax standing left, holding olive branch and caduceus.