It seems that the strategic weight of specially breeded pigeons is much higher than I thought at first, based on the number of pigeons used and the effort to stop them. (In WW2 Germans even trained falcons to hunt pigeons, so there was a whole side-battlefield of birds). Wikipedia mentions the pigeons often, but doesn't really show a lot of details or links. I thought they were mainly used by secret services, but the French troops even used mobile pigeon coops.
So my question is, how often were the pigeons used in WW1&2? The Germans seem to have learned from WW1 and trained falcons. I would be interested what kind of information (situation report from the front, secret agent report, are there some photos/protocols) was carried by pigeons and on what time scales this was done (hours, days). What average distance did these pigeons have to fly?