Rönnberg attended the British Army Staff College in 1976[2] and was promoted to lieutenant colonel on 1 October 1977.[3] He served as head of department in the staff of the Southern Military District from 1976 to 1978 and as head of the Planning Department in the Army Staff from 1978 to 1981. Rönnberg attended the Swedish National Defence College in 1981[2] and served as battalion commander in Västernorrland Regiment from 1981 to 1983.[4] He was promoted to colonel and appointed regimental commander of Västernorrland Regiment on 1 October 1982. On 1 April 1987, Rönnberg was promoted to senior colonel and was appointed military district inspector and head of the Education and Personnel Section in the staff of the Lower Norrland Military District.[3][4][6] On 1 April 1990, Rönnberg was promoted to major general and assumed the position of the last Chief of the Army Staff and of the General Staff Corps. On 1 July 1994, Rönnberg assumed the position of Chief of Staff of the Middle Military District.[2][3]
Rönnberg, Lennart, ed. (1998). Generalstabskår och generalstabsofficerare 1973-1998 (in Swedish). Stockholm: Probus. ISBN9187184559. SELIBR7762938.
Rönnberg, Lennart, ed. (1995). Arméns ledning från vasatid till nutid (in Swedish). Stockholm: Probus. ISBN9187184427. SELIBR7762926.
Rönnberg, Lennart; Borgén, Jan-Olof (1980). Försvar i framtid. Försvar i nutid, 0046-4643 ; 1980:3 (in Swedish). Stockholm: Centralförb. Folk och försvar. SELIBR206102.
^ abcKjellander, Rune (2003). Sveriges regementschefer 1700-2000: chefsbiografier och förbandsöversikter (in Swedish). Stockholm: Probus. p. 183. ISBN91-87184-74-5. SELIBR8981272.
^Rönnberg, Lennart, ed. (1995). Arméns ledning från vasatid till nutid (in Swedish). Stockholm: Probus. p. 286. ISBN9187184427. SELIBR7762926.
^Andersson, Björn (2016). Kungl Krigsvetenskapsakademien: Svenska krigsmanna sällskapet (till 1805), Kungl Krigsvetenskapsakademien : 20 år med akademien och dess ledamöter 1996-2016 (in Swedish). Stockholm: Kungl. Krigsvetenskapsakademien. p. 95. ISBN978-91-980878-8-8. SELIBR20033514.
^Moen, Ann, ed. (2006). Vem är det 2007: svensk biografisk handbok (in Swedish). Malmö: Nationalencyklopedin. p. 511. ISBN919751327X. SELIBR10171521.