When we closely observe the great battle of Kurukshetra, the armies of Kauravas were greater in number than the armies of Pandavas. 7 : 9 so to speak. Apart from the five valliant warriors, there were many great kings and queens hailing from kingdoms, big and small, who stood against the unjust.
However, in the Kaurava army, there were great warriors, valliant and famous among the former army. Yet the army of Pandavas purely relied on their knowledge and choice of standing for righteousness.

Image courtsey : Wikipedia

For example, if we see Karna and Bhishma, the great warriors, moral in character yet they both lacked the courage to rebel against the unjust they stood for. Bhishma showed the reason that he took an oath to be bound to the throne of Hastina. Karna showed the reason as he’s given everything by his friend Suyodhana, so how can he turn against him? But during the great insult that the Kauravas did to the Pandava Queen, Draupadi, none of them objected the kauravas, as the majority in the court were in their support. Yet they know they’re doing wrong.

Before the beginning of the great war, Arjuna becomes hopeless as all his trusted kins turned against the very righteousness – the god within – that he stood for. Then, Krishna reminds him of the above scenario,
though valiant they were, famous they were, they all ran away and kept on manipulating their people and not even spoke a single world against the unjust done by the kauravas.

He also explains why he spared Aswaddhama that he’s the only one, and at least raised his hand against his Kaurava friends. Thus, Krishna says that, he who sees the God within every living being, and is above the human tribulations, and stands for the righteousness, be they weak or infamous, will be victorious in the battle. The same will be applied to the self conquest. Then Arjuna realises his duty and moves ahead, and the rest is history!

-Viswanath Venkat Dasari.