Richard III opens toward the tail end of the Wars of the Roses, a series of nasty civil wars that had the Lancasters and the Yorks (two branches of the Royal House of Plantagenet) vying for the English crown. England has been enjoying newfound peace under the reign of Edward IV. This tranquility doesn't last long: Richard immediately sets out to steal the crown and takes out plenty of his family members and political rivals along the way. The play's one major battle (the Battle of Bosworth Field) is a climactic moment that brings Richard's tyrannous reign and the Wars of the Roses to an end, ushering in the Tudor dynasty and a golden age of peace and prosperity.
In Richard III warfare is portrayed as a family affair, where brothers, fathers, sons, and cousins are pitted against one another.
Although King Henry VII is not opposed to warfare, he is genuinely devoted to bringing about peace in England.