Update: The 5th Column, led by Senreich, defeated the Hunters led under Seraphna and took over the world over a 15 year period after sending them into the future. Only a few hold out places were left on Earth. After their key strong hold of London fell, it came down to a final battle with the Restored Senreich and the power of reality before the Fourth Reich - the Neo Reich - was permenantly destroyed. However, remnants of it remain due to the wide range of control they had for so many years.
Old: The 5th Column is made up of a bunch of Nazi fanatics that have held on over the hundreds of years since World War II. Led by the decayed-near corpse Senreich, who is kept alive by technology and tubes and sheer force of will, their goal has been to take over Earth and establish a new order - the Fourth Reich. Their focus has been on London due to London's resistance against them in the past.
After being defeated in The Alien Wars 3, the 5th Column was brought back to life along with everyone else when Wind and Cheryl recreated the Classic Reality. Now Senreich has once again launched his efforts, but it's clear he's joined forces with the ressurected Mavericks and other enemies who are hiding in the shadows. Together, they are using the Book of Revelations to bring about their ultimate plan to fruitation, though no one knows what it is yet.