<a href="https://en.wikipedia.org/wiki/World_War_II" id="mw2Q" rel="mw:WikiLink" title="World War II">World War II</a>: <a href="https://en.wikipedia.org/wiki/The_Hardest_Day" id="mw2g" rel="mw:WikiLink" title="The Hardest Day">The Hardest Day</a> air battle, part of the <a href="https://en.wikipedia.org/wiki/Battle_of_Britain" id="mw2w" rel="mw:WikiLink" title="Battle of Britain">Battle of Britain</a>, takes place. At that point, it is the largest aerial engagement in history with heavy losses sustained on both sides.