Are there metaphoric English expressions meaning “keeping composure at a fatal moment, never panicky”?

We have a Japanese old saying, “俎板の上の鯉－manaita no ueno koi, a carp laid on a chopping block” for describing (1) a critical situation you cannot avoid, and (2) a person who is self-poised at such a critical moment.

This metaphor comes from the legend that carp is still and composed unlike other fish, like eel when laid on a chopping board. I think it corresponds to the spirit of ‘葉隠-Hagakure’, the Bushido’s bible written by Yamamoto Tsunetomo, a senior samurai in Saga-Nabeshima fief in 1716, in which he says the ultimate goal of Bushido is to recognize when, where, how, and for what you should die.

Though I’ve never seen a carp placed on a cutting board, we use this simile for various occasions for facing predicament and requiring rational judgment / action in such a way; “The company is considering a massive layoff, I’m a carp on a chopping block,” “The governor behaved like a carp on a chopping block when he was sued for sex scandals,” "My husband said "I'm a carp on a chopping block," when he was told he was at the terminal stage of cancer by his doctor."

Are there metaphoric expressions similar to “a carp laid on a chopping block” which implies keeping composed at eleventh hour, preferably using a bird, beast, or fish, like a carp?

Solution 1:

Nerves of steel connotes the ability to control your fear and remain calm even in extremely dangerous or difficult situations.

Lionhearted, courage of a lion, etc. are also used to connote bravery.

Solution 2:

The idiom most used in British English is to maintain a stiff upper lip.

It means to retain composure in the face of adversity. A trembling lip is a sign of weakness.

Solution 3:

The phrases grace under fire and cool under fire are both used to convey calm in a difficult situation. Under fire refers to gunfire and the phrase was well adapted to the movie titled Courage Under Fire.

For an animal idiom, consider like a lamb led to slaughter. This is a phrase from the Judeo-Christian Bible, Isaiah 53:7

He was oppressed, and he was afflicted, yet he opened not his mouth; like a lamb that is led to the slaughter, and like a sheep that before its shearers is silent, so he opened not his mouth.

Solution 4:

To remain " as cool as a cucumber " is an idiomatic expression used to indicate a controlled composure in front a a difficult event.