Lose one's grip / one's cool / lose it

According to the OED, the figurative use of grip, meaning control or mastery of something or other, dates from 1450. 'Lose one's grip' meaning failing to control or master something or other, is first cited from the mid-1800s, but one gets the feeling that there must be earlier citations than this, given how old the figurative meaning of grip is. 'Lose one's cool' meaning to lose composure or temper dates from mid-1960s. Lose it, the shortened colloquial or slang version, with a narrower meaning of losing one's composure or temper, dates from the mid-1900s.