Interesting. RAF Liberators & Sunderlands (Don't think Fort's) also skip-bombed surfaced U-boats in the air-surface battles that raged across the Bay of Biscay in the Atlantic, in 1943 I believe. Norman Franks wrote a book on this little-known campaign.
Originally the U-boats used to dive, but when new weapons were used by the RAF that homed-in on the submerged sub, then the U-boats used to fight it out on the surface, when that didn't go well either then the Kriegsmarine took to forming its returning boats into small flotillas of 3 or 4 surfaced subs which fought back with flak and some right old ding-dongs erupted, some went the German way but most usually it was the RAF that prevailed, and as we all know, U-boats became almost impotent in the late war years.
