Two contenders for Army Chief Lt Gen Dwivedi, Lt Gen Singh retiring on June 30

Lt Gen Upendra Dwivedi, currently serving as the Vice Chief of Army Staff, is the senior-most official after Gen Pande.The senior most official after Lt Gen Dwivedi is Lt Gen Ajay Kumar Singh, the Southern Army Commander. But both Lt Gen Dwivedi and Lt Gen Singh, who are course mates, are set to retire on June 30, the day the extension given to Gen Pande comes to an end. What is the significance?