How is “under cover of” used?

In Mulan (2020), one line is: “I left home under cover of darkness”

Which movie is “under cover of” from?

The clip at the top of this page is from Mulan (2020).

I left home under cover of darkness

3 作品で登場 · 1 本目

hidden or protected by sth

4 本の映画に登場

オックスフォード映画の 100%
hidden or protected by sth
I left home under cover of darkness
Nothing more And then you guys send in a SWAT team under cover of night to arrest the crown Princess

定義：Oxford Advanced Learner's Dictionary 第 9 版