<a href="https://en.wikipedia.org/wiki/Thornton_Affair" id="mwYA" rel="mw:WikiLink" title="Thornton Affair">Thornton Affair</a>: Open conflict begins over the disputed border of <a href="https://en.wikipedia.org/wiki/Texas" id="mwYQ" rel="mw:WikiLink" title="Texas">Texas</a>, triggering the <a href="https://en.wikipedia.org/wiki/Mexican–American_War" id="mwYg" rel="mw:WikiLink" title="Mexican–American War">Mexican–American War</a>.