Question: Which war did the operator of the R class patrol boat serve in?

Knowledge 1: R-class patrol boat
The R-class patrol boats was a class of Finnish patrol boats, originally constructed as coastal minesweepers. They were modified into patrol boats by the end of the 1960s and transferred to the Patrol Flotilla and later to the 7th Missile Flotilla. They were then used for sea patrol and as anti-submarine warfare vessels. They were stricken from the Finnish Navy list in the 1990s. The three later vessels, "Ruissalo", "Raisio" and "Röyttä", were somewhat larger and the vessels are therefore sometimes referred to as the Rihtniemi and "Ruissalo" classes. However, the Finnish Navy used the designation R class for all five vessels. [SEP] Knowledge 2: Finnish Navy
When the Winter War broke out the Finnish Navy moved to occupy the de-militarized Åland Islands and to protect merchant shipping. In the first month of the war, battles between Soviet ships and Finnish coastal batteries were fought at Hanko, Finland, Utö and Koivisto. At Koivisto and Hanko, the batteries forced Soviet battleships to retire with damage. Finnish efforts to use submarines ("Vesikko" and "Saukko") to sink Soviet capital ships failed. In December 1939 the ice became so thick that only the ice-breakers could still move. The two coastal defence ships were moved to the harbour in Turku where they were used to strengthen the air-defences of the city. They remained there for the rest of the war.
Knowledge 1: R-class patrol boat
The R-class patrol boats was a class of Finnish patrol boats, originally constructed as coastal minesweepers. They were modified into patrol boats by the end of the 1960s and transferred to the Patrol Flotilla and later to the 7th Missile Flotilla. They were then used for sea patrol and as anti-submarine warfare vessels. They were stricken from the Finnish Navy list in the 1990s. The three later vessels, "Ruissalo", "Raisio" and "Röyttä", were somewhat larger and the vessels are therefore sometimes referred to as the Rihtniemi and "Ruissalo" classes. However, the Finnish Navy used the designation R class for all five vessels. [SEP] Knowledge 2: German submarine U-751
German submarine "U-751" was a Type VIIC U-boat built for Nazi Germany's "Kriegsmarine" for service during World War II. Built as yard number 134 of the Kriegsmarinewerft shipyard in Wilhelmshaven, she was commissioned on 31 January 1941. She served with 7th U-boat Flotilla until 1 June as a training boat, and as an operational boat until 17 July 1942, under the command of "Korvettenkapitän" Gerhard Bigalk. "U-751" served in seven patrols with the 7th U-boat Flotilla, sinking the escort carrier . The U-boat was attacked with depth charges from aircraft on 17 July 1942 and sank with the loss of all 48 crew members.
Knowledge 1: R-class patrol boat
The R-class patrol boats was a class of Finnish patrol boats, originally constructed as coastal minesweepers. They were modified into patrol boats by the end of the 1960s and transferred to the Patrol Flotilla and later to the 7th Missile Flotilla. They were then used for sea patrol and as anti-submarine warfare vessels. They were stricken from the Finnish Navy list in the 1990s. The three later vessels, "Ruissalo", "Raisio" and "Röyttä", were somewhat larger and the vessels are therefore sometimes referred to as the Rihtniemi and "Ruissalo" classes. However, the Finnish Navy used the designation R class for all five vessels. [SEP] Knowledge 2: John Kerry
During his tour on the guided missile frigate USS Gridley, Kerry requested duty in South Vietnam, listing as his first preference a position as the commander of a Fast Patrol Craft (PCF), also known as a "Swift boat." These 50-foot (15 m) boats have aluminum hulls and have little or no armor, but are heavily armed and rely on speed. "I didn't really want to get involved in the war", Kerry said in a book of Vietnam reminiscences published in 1986. "When I signed up for the swift boats, they had very little to do with the war. They were engaged in coastal patrolling and that's what I thought I was going to be doing." However, his second choice of billet was on a river patrol boat, or "PBR", which at the time was serving a more dangerous duty on the rivers of Vietnam.

Answer: Winter War