Legio I Adiutrix was raised by Nero from marines of the Imperial fleet at Misenum, when his reign as Roman Emperor was threatened in 68 AD. He did not get the chance to constitute them properly as a legion before committing suicide as the future Emperor Sulpicius Galba marched on Rome from Spain.
Galba was infuriated with their temerity and refused to hear their requests which in turn angered the legionnaries, some of them drawing swords. So Galba unleashed the troops that were with him and (according to Tacitus) many thousands were slain. He didn't stop there either, the legion was punished with decimation, a punishment that hadn't been carried out since the early reign of Tiberius as it was considered to be too humiliating for a professional, paid army. What was worse, the sentence was to be witnessed by the citizens of Rome.
To add insult to injury Galba formally constituted the legion he had raised in Spain, the VII Galbiana; therefore he granted the I Adiutrix its wish and granted it legionary status, but still went ahead and decimated them. I guess Tacitus hit the nail on the head when he wrote that Galba would make an excellent emperor, until he became emperor.
After such a bad beginning the I Adiutrix fought well at Bedriacum. They fought on the Othonian side and faced the veteran XXI Rapax, whose eagle they managed to capture. Unfortunately the enraged Rapax beat them back, capturing many of the ex-marines standards....but the Adiutrix held on to their eagle. See how they got on in Mick's refight of Bedriacum.....