Question: When was the unit associated with the earliest chief , General Rajendrasinhji Jadeja , DSO , founded ?

text: Chief of the Army Staff (India)
Appointees -- Chief of the Army Staff ( 1955–present )

The Chief of the Army Staff is the professional head, commander, and usually the highest-ranking military officer of the Indian Army. The position is abbreviated as COAS in Indian Army, and is always held by a full General. The current COAS is General Manoj Mukund Naravane, who took office on 31 December 2019.
No Name Took office Left office Time in office Unit of Commission
1 Jadeja , Rajendrasinhji General Rajendrasinhji Jadeja , DSO ( 1899-1964 ) 1 April 1955 14 May 1955 43 days 2nd Lancers ( Gardner 's Horse )
2 Shrinagesh , S. General S. M. Shrinagesh ( 1903-1977 ) 15 May 1955 7 May 1957 1 year , 357 days 19th Hyderabad Regiment
3 Thimayya , Kodendera General K. S. Thimayya Padma Bhushan , DSO , ADC ( 1906-1965 ) 8 May 1957 7 May 1961 4 years , 0 days 19th Hyderabad Regiment
4 Thapar , Pran General Pran Nath Thapar ( 1906-1975 ) 8 May 1961 19 November 1962 1 year , 195 days 1st Punjab Regiment
5 Chaudhuri , Jayanto Nath General Jayanto Nath Chaudhuri Padma Vibhushan , OBE ( 1908-1983 ) 20 November 1962 7 June 1966 3 years , 199 days 7th Light Cavalry
6 Kumaramangalam , Paramasiva Prabhakar General P. P. Kumaramangalam Padma Vibhushan , DSO , MBE ( 1913-2000 ) 8 June 1966 7 June 1969 2 years , 364 days Regiment of Artillery
7 Manekshaw , Sam Field Marshal Sam Manekshaw Padma Vibhushan , Padma Bhushan , MC ( 1914-2008 ) 8 June 1969 15 January 1973 3 years , 221 days 12th Frontier Force Regiment
8 Bewoor , Gopal Gurunath General Gopal Gurunath Bewoor PVSM ( 1916-1989 ) 16 January 1973 31 May 1975 2 years , 135 days 10th Baluch Regiment
9 Raina , Tapishwar Narain General Tapishwar Narain Raina Padma Bhushan , MVC ( 1921-1980 ) 1 June 1975 31 May 1978 2 years , 364 days Kumaon Regiment
10 Malhotra , Om Prakash General Om Prakash Malhotra PVSM ( 1922-2015 ) 1 June 1978 31 May 1981 2 years , 364 days Regiment of Artillery
11 Rao , K. General K. V. Krishna Rao PVSM ( 1923-2016 ) 1 June 1981 31 July 1983 1 year , 364 days Mahar Regiment
12 Vaidya , Arun Shridhar General Arun Shridhar Vaidya Padma Vibhushan , PVSM , MVC & Bar , AVSM ( 1926-1986 ) 1 August 1983 31 January 1986 2 years , 244 days 9th Deccan Horse
13 Sundarji , Krishnaswamy General Krishnaswamy Sundarji PVSM , ADC ( 1930-1999 ) 1 February 1986 31 May 1988 2 years , 120 days Mahar Regiment
14 Sharma , Vishwa Nath General Vishwa Nath Sharma PVSM , AVSM , ADC ( born 1930 ) 1 June 1988 30 June 1990 2 years , 29 days 16th Light Cavalry
15 Rodrigues , Sunith Francis General Sunith Francis Rodrigues PVSM , VSM ( born 1933 ) 1 July 1990 30 June 1993 2 years , 364 days Regiment of Artillery
16 Joshi , Bipin Chandra General Bipin Chandra Joshi PVSM , AVSM , ADC ( 1935-1994 ) 1 July 1993 19 November 1994 1 year , 141 days 64th Cavalry
17 Roychowdhury , Shankar General Shankar Roychowdhury PVSM , ADC ( born 1937 ) 20 November 1994 30 September 1997 2 years , 314 days 20th Lancers
18 Chowdhury , Shankar Roy General Ved Prakash Malik PVSM , AVSM , ADC ( born 1939 ) 1 October 1997 30 September 2000 2 years , 365 days Sikh Light Infantry
19 Padmanabhan , Sundararajan General Sundararajan Padmanabhan PVSM , AVSM , VSM , ADC ( born 1940 ) 1 October 2000 31 December 2002 2 years , 91 days Regiment of Artillery
20 Vij , Nirmal Chander General Nirmal Chander Vij PVSM , UYSM , AVSM , ADC ( born 1943 ) 1 January 2003 31 January 2005 2 years , 30 days Dogra Regiment