Though not unexpected, it was a shock to Dr. Nygaard that Norway was occupied by the Germany April 9, 1940.  He was, however, to make his contribution to fighting the war as a doctor for Norwegian sailors during The Second World War. The Norwegian Merchant Marine consisted of 1000 ships and 25.000 men whose task it was to ship commodities and war military equipment between the allied countries.

New York became the largest convoy port in the world, and many sailors arriving there had need of medical attention.  A Norwegian health clinic was established, with Nygaard as a surgical consultant.  He would perform minor out-patient surgery there, while more complicated cases had to be transferred to White Plains Hospital.  On busy days the clinic might have 250-300 patients.

Dr. Nygaard persuaded the administration of White Plains Hospital to establish a separate wing at the hospital for Norwegian sailors with 35 beds, jokingly called "The Grand Hotel" by Nygaard himself.  He was called on at any time of day or night, and his working hours might be 16 or 18 hours a day.  He performed treatment and care of the sailors far beyond the purely medical.  He treated the complete person the way he had learned at the Mayo Clinic.

In this work for the sailors, his wife Ella Nygaard also contributed. She became like a mother to many, her presence had a soothing effect on them. She initiated a Norwegian library at the wing, assisted sailors practically, and not least - she organised visitor's groups.

Both Kaare and Ella were honoured for their work during the war. Kaare was appointed a Knight of the Order of St. Olav, First Order, and this same occasion Ella Nygaard and The White Plains Hospital were awarded a Diploma of Gratitude from the King of Norway.