Sentence:  The soldiers swept into the trench with a cheer! Some of the Turks remained to argue the point with the Australians, but the bulk of them ran squealing, for fear of being stuck, like pigs, to the second trench. Those Turks who stopped to argue, argue no more. `Advance, Australia!' resounded through the bushes. `Into the cows! <WSD>Bog in</WSD>, boys, <WSD>bog in!</WSD>' 
Meaning of the word marked with <WSD> tags:  To tackle a task vigorously.