Rabaeus was born on 4 May 1917 in Vara, Sweden, the son of the senior teacher David Ohlson and his wife Ingegärd (née Bengtson).
[1] He passed his studentexamen from Katedralskolan in Skara in 1937[2] and took a reserve officer exam in 1940.
Rabaeus received a Master of Philosophy degree from Uppsala University in 1946 and became attaché at the Ministry for Foreign Affairs in 1946.
[1][3] Rabeus was embassy counsellor in Paris while serving in the Organisation for European Economic Co-operation delegation from 1957 to 1959.
He was director at the Foreign Ministry from 1959 to 1961, embassy counsellor in Paris from 1961 to 1963 and ambassador in Algiers from 1963 to 1966.