The End of Time (The Castleton Series) 2nd edition

In the distant future, technology has disappeared and humans have been reduced to a handful. This remnant lives a simple, peaceful existence, until an unidentified invader arrives -- yellow in color, shaped like cross between a knight in armor and a football player -- killing all the people they find. The villagers call them Dandelions, because they are yellow and just popped up. Charlie Newcomb escapes and travels back seven generations to seek the daring and innovative time crew described in his ancestor?s diary. Freshly returned from studying the Battle of Agincourt for a UNH professor, Mike Castleton, Patrick Weaver, and Nick Pope had witnessed the power of the English long bow. With this simple weapon a handful of English archers had destroyed an army of French knights. The CT9225?s crew answers Charlie?s desperate plea for help. With their friends Allie Tymoshenko, Jen Canfield, and Lenore Smith they return with Charlie to lead the humans in battle with the Dandelion army, and perhaps witness the end of time.