Allegedly he wanted to kill Queen Elizabeth II - with a crossbow.
In revenge for a massacre carried out by British soldiers on Sikhs in the northern Indian city of Amritsar in 1919.
But the masked Jaswant Singh Chail didn't get very far.
He was arrested on December 25, 2021 in the grounds of Windsor Castle before he could get to the monarch and her family.
Chail is a British citizen but also describes himself as an “Indian Sikh”.
Shortly after the arrest, the 95-year-old Queen's Christmas speech was televised.
It was her first since her husband Prince Philip died last summer.
Now the 20-year-old Chail has been charged with treason.
He wanted to at least injure or frighten the queen with a weapon.
The man from Southampton has to answer in court in London in two weeks.
The last time a man was charged with the same crime was more than 40 years ago.
At that time, Marcus Sarjeant shot Elizabeth II six times on the London Mall, but only with blank cartridges.
On June 13, 1981, the Queen rode her horse in the annual Trooping the Color parade, held in her honor.
Sarjeant then pleaded guilty and was sentenced to five years in prison.
In Queen Victoria's day, he would probably have been executed for what he did.
However, the monarch, who was herself the victim of several assassination attempts, had the relevant law amended in 1842, also on the recommendation of her husband Prince Albert, and introduced a new criminal offence.
High treason turned into treason, anyone who only hurt or frightened the monarch should get a milder sentence.
Jaswant Singh Chail was also charged under the Treason Act 1842 on Tuesday.