<a href="https://en.wikipedia.org/wiki/World_War_II" id="mw4g" rel="mw:WikiLink" title="World War II">World War II</a>: <a href="https://en.wikipedia.org/wiki/Imperial_Japanese_Navy" id="mw4w" rel="mw:WikiLink" title="Imperial Japanese Navy">Imperial Japanese Navy</a> <a href="https://en.wikipedia.org/wiki/Midget_submarine" id="mw5A" rel="mw:WikiLink" title="Midget submarine">midget submarines</a> begin a series of <a href="https://en.wikipedia.org/wiki/Attack_on_Sydney_Harbour" id="mw5Q" rel="mw:WikiLink" title="Attack on Sydney Harbour">attacks on Sydney</a>, Australia.