Definice a Význam "[step] into the breach"

What is the origin of the idiom "step into the breach" and when to use it?

The idiom "step into the breach" comes from military terminology, where a "breach" referred to a gap in a defensive position. It has been in use since at least the 16th century. Today, it is used to describe a situation where someone takes over a difficult task or responsibility in a crisis or emergency situation.