The Brandenburgers next saw action in the spring of 1940. In April, small detachments operated in Scandinavia. In May, the Brandenburgers seized objectives in France and the Low Countries, directly contributing to the success of the blitzkrieg. Brandenburgers, dressed in enemy uniforms (with German uniforms underneath, to avoid being shot as spies if captured) and speaking the enemy's languages fluently, infiltrated through the enemy front and took many objectives by ruse or by force.

When all went well, German spearheads arriving a few hours later would receive intact bridges or other objectives from the Brandenburgers. In the western campaign, the Brandenburgers met with great success and took 42 of 61 objectives, including:

• The important Gennap (Netherlands) railroad bridge, the Roermond (Netherlands) bridge, and Stavelot (Belgian Ardennes) bridge in the opening hours of the campaign.
• A critical bridge over the Meuse River for the 7th Panzer Division.
• The Nieuport sluice gates and pump house on 27 May, thereby preventing the Allies from flooding portions of northern Belgium and impeding German operations there.

In June 1940, the Brandenburgers expanded to regiment size. Designated "Construction-instruction Regiment 800", the regiment initially contained three battalions, with home stations as shown:

Construction-Instruction Regiment 800

I Bttn: (1-4 Companies) Brandenburg-am-Havel
II Bttn: (5-8 Companies) Baden-bei-Wien
III Bttn: (9-12 Companies) Aachen (later at Duren)

Over the course of the next year, the regiment slowly continued to expand, forming a signals units, a tropical company, and various other companies. (The IV battalion, formed May 1941, appears to contain administrative and support units, although I haven't fully confirmed this.) In this period, Abwehr II planned operations to support an invasion of England and an assault on Gibraltar, but all were canceled when Germany turned its attention to Africa and the east.

Brandenburgers

1939: Origins and Early Operations
1940: Triumphs and Expansion
1941: To Africa and Victory in the East
1942-1943: Operations and Re-organization
1944-1945: Eclipse and Defeat
Europa Order of Battle