Green’s Dictionary of Slang

Dutch courage n.

also courage, Dutch nerve, ...spunk, German courage
[coined as a propagandist measure during various Anglo-Dutch wars of 18C]

1. [19C+] cowardice that, fortified by generous quantities of alcohol, becomes (temporary) bravery; also as fortified by drugs; also attrib.

2. [mid-19C] in fig. use, courage that is obtained through some form of non-alcoholic extra-personal aid, e.g. a weapon.

In phrases