<a href="https://en.wikipedia.org/wiki/American_Civil_War" id="mwTg" rel="mw:WikiLink" title="American Civil War">American Civil War</a>: <a href="https://en.wikipedia.org/wiki/Union_(American_Civil_War)" id="mwTw" rel="mw:WikiLink" title="Union (American Civil War)">Union</a> forces engage <a href="https://en.wikipedia.org/wiki/Confederate_States_of_America" id="mwUA" rel="mw:WikiLink" title="Confederate States of America">Confederate</a> troops at the <a href="https://en.wikipedia.org/wiki/Battle_of_Pea_Ridge" id="mwUQ" rel="mw:WikiLink" title="Battle of Pea Ridge">Battle of Pea Ridge</a> in northwestern <a href="https://en.wikipedia.org/wiki/Arkansas" id="mwUg" rel="mw:WikiLink" title="Arkansas">Arkansas</a>.