How is “march on” used?

In The Great Dictator (1940), one line is: “that we are at last ready to march on Osterlich.”

Which movie is “march on” from?

The clip at the top of this page is from The Great Dictator (1940).

to march to a place to protest about sth or to attack it

Heard in 9 movies

Oxford100% of films
to march to a place to protest about sth or to attack it
that we are at last ready to march on Osterlich.

Definitions from the Oxford Advanced Learner's Dictionary, 9th edition

that we are at last ready to march on Osterlich.

Said in 8 films · #1