As an underground armed organization, members did not normally call it by its name, but rather used other names.

The party then began to operate as an underground organization.

However, various underground organizations soon started to grow and the students became their leaders in Warsaw.

In large parts of the country, the local underground organisations took over the movement.

They had the idea that we were doing underground organization.

He belonged to so many secret and underground organizations that he'd almost lost count.

From his early youth he took an active part in the underground organization.

During the late 1860s and 70s a series of revolutionary underground organizations was formed.

Those who continued to operate did that as underground organizations.

Checking in with an underground organization for my next target.