On March 17, 1944, Mt. Vesuvius began erupting and continued for several days. There were numerous Army and Air Force units stationed in the immediate vicinity, and the records of the 47th Bombardment Group verify that they were stationed at 
Vesuvius Field from January 10, 1944 to March 21, 1944, when the group relocated to Capodichino. Cy doesn’t say much about the eruption or the disruption it caused, in his letters at this time. For a good account of the eruption with photographs see: https://www.earthmagazine.org/article/benchmarks-march-17-1944-most-recent-eruption-mount-vesuvius .
In his letter of November 13, 1944, Cy finally describes the night of the eruption as follows:
In the show last night (we have three per week, all first line) they showed some pictures of Naples, one of which showed Vesuvius popping over last winter. At that time, I was working five miles from Cassino as a liaison officer.
I went in town the night before my leave started, and when my driver drove me out to the camp, on the slopes of Vesuvius, it was about three A.M. I could see the long snaky trail of red lava, and thought I was really plastered, for I hadn’t heard anything of it up to that time. During the night we had several small earthquakes, which I naturally attributed to the vino, as well as some torpedo juice I had drunk (pure alcohol with a dash of canned grapefruit juice).
In the morning I woke up to find the camp covered with fine red ash, and a most startling collection of crap flying through the air a thousand feet above. After checking the wind direction and a few other factors, I decided that if we expected to get out of there with any of our equipment, we’d better do it quickly; and as usual, the OM was drunk. We got together on the latrine and had a long conference, the result of which was that we evacuated.
Just before I flew the last ship out, a couple of G.I. photo men came along and asked for a ride to get some pictures of the part which was really messed up. I threw them in, and flew through a pile of the falling ash and rocks, and then up around the column of smoke which was 35,000 feet high, incidentally. The airplane was a wreck, I was a nervous wreck, and the damn photo men were so scared they didn’t take a single picture.
There were hunks of rock 150 feet long and 30 feet in diameter being blown out of the mouth like tooth picks. The whole top of the mountain changed in shape, and the lava dust covered up areas as far as 300 miles away. Airplanes flying into the haze of dust and cinders 200 miles away had all of the paint eroded from them.
That’s one you can tell the grandchildren, Toots, as it is the worse scare the OM has had in this war. Lots of love, Cy.