There is so much history in WWI that I never learned. I learned when it started, possibly the catalyst that started the War to End All Wars and when America officially entered, but I didn't realize how many countries outside of Europe were affected. I thought Lawerence of Arabia was set WAY before 1900's!
Among the 600,000 killed were tunnelers; specialized soldiers who dug tunnels under the German lines. Most were actual miners from Australia, Canada and Britain. They used the tunnels to pack in explosives to blow the enemy defense.
The Germans figured out what was going on and counterattacked with their own tunnelers. Sometimes fighting went on deep underground.
One of the biggest victories was when Hill 60 was taken in the Battle of Messines (Battle of the Mines or The Mine Battle):
"Hill 60 was captured by the 11th Battalion
West Yorkshires on 7 June 1917 during the Battle of Messines, when two
huge mines were blown; one on the Hill itself which was a charge of more
than 53,000 lbs blown by the 1st Australian Tunnelling Company, whose
memorial is on the Hill, who also blew the neighbouring Caterpillar
The surprise, the impact and the chaos amongst the Germans were
complete. It was the most important Allied military victory of the war
up to that point. The Messines-Wijtschate salient was eliminated. Units
from Ireland, New Zealand and Australia took part in the battle...
The hill remained behind the British lines, and in early 1918,
Australian Engineers built an Observation Bunker on the eastern side,
with good views across Battle Wood towards Hollebeke. The Hill fell into
German hands again during the Battle of the Lys in April 1918, and was
recaptured by British troops, with American units on their flanks, in
the Fourth Battle of Ypres in September 1918."
I found this information and pictures here: