Keilhau realised that war was coming in the early part of the twentieth century and she traveled internationally to make ready.

[2] Keilhau was credited with inspiring the Norwegian Red Cross to take an active role to relieve suffering during the First World War.

[2] In 1915 she was chosen as the Norwegian delegate to a peace conference in the Hague.

[1] Delegates were called from around the world although many had difficulties attending because the peace efforts were "only" of women and hostilities made travel difficult.

[3] At the conference, she proposed resolution 28 that "We women, in International Congress assembled, protest against the madness and horror of war, involving as it does a reckless sacrifice of human life and the destruction of so much that humanity has laboured through centuries to build up.