Hello
Just found this a few minutes ago and I am delighted. A online collection of war posters at the Portuguese National Library.
Link:
I Guerra Mundial, Cartazes da Colecção da BN (check the galeria)
Some samples:
the above one is about munitions... (amazing ahn?)
the last one is from 1923, asking for 2 minutes silence in memory of the fallen in battle of La Lys (Battle of Estaires for the anglos, a forgoten detail in the big WWI history but with big repercursions in Portugal at the time. Sorry, I saw this and it just winded me up...)