<Ul> <Li> Ypres Salient </Li> <Li> Hooge in World War I </Li> <Li> Wurst Farm </Li> <Li> Celtic Wood </Li> <Li> Messines mines </Li> <Li> Operation Hush </Li> <Li> Nieuport, 10--11 July </Li> <Li> Tactics, 1917 </Li> <Li> The Menin Road (painting) </Li> </Ul> <Li> Hooge in World War I </Li> <Li> Nieuport, 10--11 July </Li> <Li> Tactics, 1917 </Li>

Why was the third battle of ypres important