By all accounts, Mario is a mercenary working for the Mushroom Kingdom royal family. He has been on their payroll for decades and his main purpose in this political landscape is to be their guard dog, their loyal unit the family sends when there is unrest or military operations of any kind to complete.

He was therefore used to quell the various Bowser rebellions, and has been confirmed to have been instrumental in the Sarasaland Invasion of 1992, which saw the royal family deposed and Princess Daisy installed in their place as a puppet.

Below is a rough diagram of Mario’s unique appearance and the functions of his military uniform:

Mario’s history begins in Italy, where he lived until he mysteriously vanished from records only to reappear 6 years later in the Mushroom Kingdom, fighting against the first of Bowser’s rebellion.

Considering the timing and context, it is likely that Mario was active in the Years of Lead as a CIA local hire. During those times, the CIA payrolled Italian fascists to commit arson, kidnapping and other various acts of terrorism to create instability in Italy and prevent a communist revolution.

Where did Mario learn to fight? This answers the question.

He was then likely sent to the Mushroom Kingdom (as we know from Files #1 that the CIA materially and financially supports both the royal family and Bowser, playing both sides against each other) but it is unknown whether Mario remains on the CIA payroll today. It is more likely that he founded a mercenary company in the Mushroom Kingdom with his “brother” Luigi (a cover story).