Steve wrote asking about the connection between World War II and the diaconate, especially in Europe. This is extremely important for understanding the contemporary order of deacons, so thanks, Steve, for a chance to sketch out some things.
In Germany and France during the 1800's, there was considerable discussion about reconnecting "the church" with the people. There was a growing concern that a rising individualism had become prevalent, with a kind of "me-and-Jesus" spirituality developing, even in public worship. So, for example, the Benedictine monks in Solesmes, France, around 1840, began a program of liturgical renewal with the goal of increasing lay participation at the Mass. About the same time in Germany, discussions took place about how to help connect the Gospel with everyday life, and some people even suggested that having deacons, who would have a mission from their bishop and who would still be living among the people they served (and not, for example, in a rectory), would be a big help. There was also a growing appreciation that the Church's identity involved the care and service of others and this also became associated with the desire for a renewed diaconate, since this had been a major responsibility of the deacons in the ancient church as well.
These discussions continued into the 20th century. Then in January of 1933, Adolf Hitler came to power in Germany. He began to nationalize various aspects of German life (banking, for example) and there was concern that he would try to nationalize the charitable agencies already being run by both Protestant and Catholic groups. Second, Hitler opened the first concentration camp at Dachau, just outside of Munich. Into Dachau went many of those who opposed his policies, including, over time, several thousand German (and later, Polish) priests.
At first, religious leaders (rabbis, sisters, priests, bishops, ministers) were ordered to live within the general prison population, with no special treatment accorded them because of their religious role. Therefore, many of the cell blocks had spiritual leaders present among their fellow prisoners, able to minister to them. Eventually, the Nazis realized that this was giving people strength to continue to oppose them, so they emptied out a cell block (eventually several blocks) and placed the clergy there in an attempt to isolate them; it didn't work, and the clergy would still sneak into other areas and minister as they could. The Nazi guards referred to Cell Block 26 as "The Priest Block." This new arrangement also gave the priest-prisoners mutual support as well as the chance to talk and to dream.
Over time, these religious leaders began to ask themselves why their efforts to prevent war and violence and destruction had been so ineffective in the first decades of the 20th Century. Imagine if you were a 45-year old German priest in 1945 at the liberation of Dachau. You would be thinking about things like the First World War when you were a teenager; the rise of the various totalitarian regimes; the worldwide economic collapse, and on and on. And now, you have the experience of being in a concentration camp and experience the hell of the Shoah. What could the Church do to be a more effective witness of Christ to this world? That's the question for the future. It is no coincidence, that many of the leaders for reform at the Second Vatican Council were bishops from places so profoundly affected by the Second World War: Germany, France, Belgium and so forth.
Among the variety of things that these priest-prisoners began to discuss (and they talked of MANY things!) was the possibility of a renewed and permanent diaconate which would work in concert with priests, with deacons serving as icons of Christ the Servant who gave himself totally in service to others. This was an important lesson that these people learned in the camp: that it was the care of others that perhaps could provide the most powerful sign of Christ's presence. This would be the responsibility of a new cadre of deacons.
After the war, two of these priest-survivors (both German Jesuit priests) eventually began writing about these conversations at Dachau, and their writing drew the attention of a variety of laity, priests and bishops, especially in Germany and France. Diaconal groups were formed to study and to plan for a renewed diaconate, and all of this activity drew the attention of theologians, especially Karl Rahner, who became a real proponent of the idea. Throughout the late 1940s and into the 1950s, many scholars and groups began to discuss the diaconate so intently that in 1957, Pope Pius XII spoke about the possibility. Even though he felt that "the time is not yet ripe" [in 1957] to take this step, he indicated that he was in favor of the idea. Karl Rahner, just before the Second Vatican Council began, wrote a 536-page book on the diaconate that has never been completely published in English. However, he made the German edition available to the bishops of the world.
Eventually, there would be more than 100 recommendations for a renewed diaconate received BEFORE the Council began, representing more than 200 bishops from around the world. About 60% of these recommendations came from Western and Eastern Europe.
That's a quick sketch, Steve. Hope that helps a bit!