How is “split down the middle” used?

In Michael Collins (1996), one line is: “The army's split down the middle.”

Which movie is “split down the middle” from?

The clip at the top of this page is from Michael Collins (1996).

Idiom

to divide sth into two equal parts

Heard in 8 movies

split / divide sth down the middle
to divide sth into two equal parts
The country was split down the middle over the strike (= half supported it, half did not).

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

The army's split down the middle.

Said in 8 films · #1