Vice Admiral Alfred Erik Bertil Berthelsson (11 April 1902 – 11 February 1977) was a senior naval officer in the Swedish Navy.

After service as an acting sub-lieutenant on the coastal defence ship Sverige with Göran Wahlström as executive officer and long voyage with the cruiser HSwMS Fylgia to South America, Berthelsson began his training as an air scout.

[2] However, in the autumn of 1942, Berthelsson had already taken up the position of teacher in tactics at the Royal Swedish Naval Staff College and in 1943 was appointed lieutenant commander.

Berthelsson's good handling of investigative issues led him to be appointed as an expert in the 1945 Defense Committee as an assistant to the then Rear Admiral Stig H:son Ericson, who was the navy's representative.

[2] Berthelsson's longing for a tour of sea duty was satisfied in the autumn of 1947, when he took over as destroyer division commander with base aboard Visby.

Tre Kronor was therefore allowed to act fairly independently under the command of the captain, during which Berthelsson was free to develop his thoughts on tactics and personnel care.

It was a time when Swedish naval ships was fully equipped with radar, both for reconnaissance, combat command and navigation as well as for weapons deployment in many different forms.

In the autumn of 1951, Berthelsson was appointed flag captain of the Coastal Fleet, whose commander was Rear Admiral Stig H:son Ericson.

At the organizational reductions, Berthelsson preferred to reduce the land organization in order to keep the crews on board, which led to some contradictions.

The increasing number of investigations with which the navy was charged during Berthelsson's time as chief meant that his agility, acquired through dealings with publicists and politicians, came in handy.

However, in 1958 - due to drastically cut defense spending - the destroyers Lappland and Värmland had to be canceled to get funds available for the acquisition of the ship types that would be part of the new light fleet, which would succeed the cruiser era.