Quod Iam Diu (1918)

Quod Iam Diu was an encyclical of Pope Benedict XV, given at Rome at St. Peter’s on December1, 1918, the fifth year of his Pontificate. It requests all Catholics everywhere in the world, no matter which side they were on, to pray for a lasting peace and for those who are entrusted to make it during the upcoming peace negotiations.
(From Wikipedia)