Worked for SBI and served army in emergency but not given promotion

I need help to file a writ against State Bank of India. I joined State Bank of India as a directly recruited officer in 1957. In 1963, when the first National Emergency was declared, I volunteered for Army Service. I was selected by the Army and deputed for Army Service by State Bank of India. When the emergency ended in 1967, I returned to the bank. I was shocked and surprised to find that the bank had not considered me for any promotions during the entire period of my Army Service whereas officers of my seniority and and some junior officers had been promoted. I was in limbo during the entire 4 year period. I was understandably aggrieved and asked the bank for an explanation. The bank responded that my Army Service was not relevant to the work of the bank. I was shocked by this response: why had the bank deputed me if the deputation was not relevant to the bank's work?