The Commonwealth of Britannia (ブリタニア連邦 ?) is a country in northwestern Europe, which is similar to modern Great Britain. It is the setting for most of the first season of Strike Witches.
Their nation's insignia seems to be a small red disk on a larger blue circle superimposed on a wider white circle outlined with another yellow circle. Britannia was the Front Line of the Neuroi War and the Battle for Gallia.