<a href="https://en.wikipedia.org/wiki/World_War_II" id="mwzg" rel="mw:WikiLink" title="World War II">World War II</a>: The <a href="https://en.wikipedia.org/wiki/Battle_of_Hel" id="mwzw" rel="mw:WikiLink" title="Battle of Hel">Battle of Hel</a> begins, the longest-defended pocket of Polish Army resistance during the German <a href="https://en.wikipedia.org/wiki/Invasion_of_Poland" id="mw0A" rel="mw:WikiLink" title="Invasion of Poland">invasion of Poland</a>.