Roundheads were Parliamentary/Puritan soldiers who wore tight fitting un-orimented metal helmets, while Cavaliers were kings men who wore large hats with feathers as their uniform headdress.
Some differences between the round-heads and the cavaliers are that the cavaliers supported the King and the round-heads supported Parliament.
The movable type printing press.
<u>Unrestricted Submarine Warfare</u> and <u>Zimmermann Telegram</u>