Answer:
Their behavior at the first sign of danger was craven, a stark contrast to the bravery expected of those wearing the uniform.
Explanation:
The question is not clear. Are all the words to be used in a new sentence? If only one word is to be replaced, then:
Their behavior at the first sign of danger was craven, a stark contrast to the bravery expected of those wearing the uniform.
Craven means cowardly or lacking courage, perfectly capturing the disdain implied by the original statement.
