How did feminists come up with the expression “male chau-vinist pig”?

The word chauvinism originally meant excessive patriotism and came
from the name of Nicolas Chauvin, a French general who was known
for his extreme devotion to Napoleon Bonaparte. “Male chauvinism”
became a description of a man preoccupied with masculine pursuits
during the 1950s, and the word pig, borrowed from a slur on police-
men, was added by the women’s movement in the 1970s.