"Arturia is the daughter of British King Uther Pendragon and Igraine, a former Duchess of Cornwall. At her nativity, Uther realizes his subjects will never accept a female as a legitimate ruler, and decides to not publicly announce Arturia's birth or gender. She is entrusted by Merlin to a loyal knight, Sir Ector, who raises her as a surrogate son. When Arturia is fifteen, King Uther dies, and with no known eligible heir to the throne, Britain enters a period of turmoil following the growing threat of invasion by the Saxons. Merlin soon approaches her, explaining that the British people will recognize her as a destined ruler if she withdraws Caliburn, a ceremonial sword embedded in a large slab of stone. However, pulling this sword is symbolic of accepting the hardships of a monarch, and Arturia will be responsible for preserving the welfare of her people. Without hesitation, and despite her gender, she draws Caliburn and shoulders Britain's mantle of leadership.

Arturia rules Britain from her stronghold in Camelot, and earns the reputation of a just, yet distant king. Under the guidance of Merlin and with the aid of her Knights of the Round Table, she guides Britain into an era of prosperity and tranquillity. Caliburn is destroyed, but Arturia soon acquires her holy sword, Excalibur, and Avalon, Excalibur's blessed sheath, from Vivian. While Avalon is in her possession, Arturia never ages and is immortal in battle."

Wikipedia.

I loved Fate Stay Night so I had no choice but to do this piece. I wanted people who haven't seen the show to know a little about the background of the character which is why I've included the Wiki text. If you've seen the show I think the picture might make a bit more sense to you. Comments are encouraged. Thanks!