This article of 50 years ago encouraged each bishop to care about the world outside his diocese
....to send some priests to mission areas

As far as I remember (please correct me if you have better information)
three (3) out of Australia's (then) 30 something dioceses
sent some priests to mission areas as a result of the above plea by Vatican II

No doubt most bishops at the time said "we haven't got any priests to spare".
And maybe in most dioceses the priests themselves were not keen to sacrifice any of their number.

A bit different was a bishop of Marseilles 200 years ago. He was extra short of priests after the decimation of the French Revolution. But when a missionary bishop from Canada asked him for help, he sacrificed some of his priests.
The missionary bishop later said "Go to Marseilles and you will find someone with a heart as big as St Paul's".
The priests who went to Canada eventually attracted some 2,000 local Canadian men who became priests.
Name of Marseille bishop: Eugene de Mazenod

Jesus, please give all bishops the heart of Eugene de Mazenod