In the South Pacific, the Navy used them in WW2.
They were invented BEFORE WWI and yes they were also used, somewhat, in WWII but the browning .30 cal in the water cooled and air cooled versions were used much more extensively. The Lewis gun was far better known in WWI than it ever was in WWII. Plus the article states it was a WWI relic. Some people just like to argue I think.