In 1914, the poor little Belgians retreated behind the Yser river, during 4 years the Belgians stayed there, because King Albert I didn't believe the optimistic British and French generals who came joyfully announce their next lagre attack (mass slaughter), and claimed it would be the end of the war in the trenches, plus if the Belgians did attack then they would get slaughtered and the path to Calais would be free.

However in 1918, the last major offensive of the allies was coming up, victory was a certainty and out of political reasons Albert I decided to contribute.
The other allied forces were surprised by the strength and organization of the Belgian Army, Poor Little Belgium, grew to become Brave Little Belgium