If you'll recall, when the young King Edward VI was dying at age fifteen, he made a rather interesting and shocking decision to erase his half-sister Mary's name from the line of succession. Edward was a Protestant King - the first true Protestant monarch on the English throne, and he therefore wanted no part in the very-Catholic-Mary taking the throne upon his death. It was probably very clear to everyone at court (and possibly all around England), that Mary's sole purpose once taking her place as Queen would be to restore England to Catholicism. She saw this as her purpose in life after her father King Henry VIII had shockingly broken ties with the Pope and annulled his marriage to her mother during Mary's childhood. Of course, Protestant Edward could not allow this to happen, so he replaced Mary's name with his cousin, Lady Jane Grey's. A fellow Protestant and also young like himself, Edward saw Jane as the perfect next Queen. Of course, this did not only shock England - it shocked Jane also, who saw Mary as the rightful heir.
I already wrote a post about how, on July 10th, Lady Jane Grey was proclaimed Queen on the same day that Mary Tudor wrote to the Privy Council asking for their allegiance. Sad to think that these events happened on the same day, but Mary must have had some clue that things in London were taking an unexpected turn. By July 12th, Mary had assembled a military force in Suffolk and it was clear that her followers were growing. People wanted Mary on the throne. Protestants and Catholics alike saw Lady Jane Grey as an imposter, which is so sad for her, since she wanted no part in it to begin with.
Unfortunately for Jane, Mary and her retinue of supporters entered London on July 19th and Jane was deposed. And so her nine-day reign was over. She, along with her husband Guildford Dudley and her father-in-law John Dudley were imprisoned in the Tower of London while Mary enjoyed her return to London.
Think not, Tudor Enthusiasts, that Mary had the same reputation then that she would have later in her reign! Oh no - Mary had a flock of support from across the country, though of course there was fear in her ascension also - as Edward VI had suspected there would be. People were nervous about how Mary would go about restoring England to Rome - (and it turns out that they were right to be fearful.