when did the battle of antietam begin

William and his awesome friend Jason bring their bicycles on the attic, shrink themselves, and go on an adventure. They meet Sir Simon as they is getting ready to leave for any tournament, and so they remain at his castle. They spend time with a boy along with a girl with the castle and together. The girl tells them associated with an omen her grandmother, Calendar, kept repeating before she died. Sir Simon sent Calendar away towards the convent while he thought she was crazy and that he doesn't believe the omen. Few accept is as true but Calendar's granddaughter does. Jason and William believe it too.