1937 Vatican card of Eugene Cardinal Pacelli's thank you note on behalf Catholic Pope Pius XI giving an APOSTOLIC BENEDICTION
5 1/2" wide X 4 1/2" tall on Vatican stationary with the coat of arms and "Segreteria di Stato di Sua Santita" "Secretary of State of His Holiness".  The message is written in English
 
"May 18, 1937
Eugene Cardinal Pacelli, Secretary of State to His Holiness begs to express the heartfelt gratitude of the Holy Father for the filial good wishes and for the loving assurance of prayers sent Him in His illness and to convey in pledge of plenteous and abiding grace, His paternal Apostolic Benediction."
 
This was written before Eugene Cardinal Pacelli became Pope Pius XII in 1939. Pope Pius XII was a very controversial Pope and the start of the pontificate of Pius XII occurred at the time of the Second World War and the Nazi Holocaust in 1939 and through communism when died in 1958.
 
The Apostolic Blessing or papal blessing is a blessing imparted by the Pope, either directly or by delegation through others. Bishops are empowered to grant it three times a year and any priest can do so for the dying.