On this date in 1937 (Easter Sunday that year) Pope Pius XI published Firmissimam constantiam (Firm Constancy), his third encyclical addressing the struggle in Mexico.

Firmissimam Constantiam ( March 28, 1937)

Venerable Brethren, Health and Apostolic Benediction. There is well known to Us, Venerable Brethren - and it is a great cause of consolation for Our paternal …