There are a number of ongoing and forthcoming events and exhibitions in Cambridge associated with the anniversary of the start of the First World War, known sometimes as the Great War. At the Fitzwilliam museum for example there is an exhibition of French wartime prints (La Grande Guerre), and at the Folk Museum an exhibition of textiles made by soldiers recovering at the Cambridge military hospital (Between the Lines).
The Great War made arguably as great a psychological mark on the British as the Second World War, in spite of the fact that it was not such a naked struggle for survival, owing not only to the vastly inflated casualty lists of WWI compared to WWII, but to the almost surreally futile nature of much of the combat, played out, in imagination, over a few muddy yards in France and Turkey.
I’m not sure when or why upcoming replaced forthcoming, as in upcoming events at the Fitzwilliam, but its victory seems to be complete. Perhaps it is a little snappier, a little sharper; perhaps forthcoming is a little fusty.
Upcoming derives, I imagine, from the phrasal verb. Events can come up, and it has the right Anglo-Saxon ring to it. Forthcoming on the other hand smacks of the printing press, of pamphlets or books issuing forth. And it has another meaning: a person can be either forthcoming or uncommunicative. So it could be that what we have is an acceptable shuffling of meanings – acceptable because something is won, in the end, not lost. A nuance.
It is not always the case. Someone I follow on Twitter recently threatened to unfollow (now there’s a verb) anyone who used amongst rather than among, or whilst rather than while. He said the alternative forms were pretentious. But this seems to me a loss, tonal rather than semantic (certain sounds will elide better after the dental st than the nasal ng).
Non-native readers need not panic. This is a purely internal struggle, part of the ongoing but almost invisible struggle for the soul of the language. Hardly a war to end all wars.