Simplify the following text for a Grade 7 native English-speaking person.
Original: The Condor Legion was a unit composed of volunteers from the German Air Force ( Luftwaffe ) and from the German Army ( Wehrmacht Heer ) which served with the Nationalists during the Spanish Civil War of July 1936 to March 1939 .
Simplified: The Condor Legion was a unit of `` volunteers '' from the German Air Force ( Luftwaffe ) . This group served during the Spanish Civil War of July 1936 to March 1939 .