He took 4th at Stockholm 1934 (Erik Lundin won), tied for 3rd-4th at Falun 1934 (Lundin and Olof Kinnmark won), tied for 3rd-4th, behind Paul Felix Schmidt and Paul Keres, at Tallinn (Reval) 1935, and won at Göteborg (Gothenburg) 1935 (Quadrangular).
In September 1935, he played at a match Sweden vs Germany (Scheveningen system) in Zoppot (Sopot). In 1937, he tied for 3rd-4th in Stockholm (Reuben Fine won). In 1939, he took 6th in Alingsås (Gideon Ståhlberg won).
Danielsson represented Sweden in Chess Olympiads:
- In 1935, at fourth board in the 6th Chess Olympiad in Warsaw (+12 -1 =6)
- In 1936, at fourth board in 3rd unofficial Chess Olympiad in Munich (+9 -2 =9)
- In 1937, at fourth board in 7th Chess Olympiad in Stockholm (+12 -2 =4)
- In 1939, at fourth board in 8th Chess Olympiad in Buenos Aires (+7 -3 =5)
- In 1952, at second reserve board in 10th Chess Olympiad in Helsinki (+1 -2 =3)
He was a Swedish Champion in 1955.
- Gaige, Jeremy (1987). Chess Personalia A Biobibliography. Jefferson, North Carolina: McFarland & Company. p. 84.
- Other sources says Hagalund
- OlimpBase The encyclopaedia of team chess
- Gillam, Anthony J. (1999). Munich 1942, 1st European Championship. Nottingham: The Chess Player. ISBN 1-901034-46-1.