Bhagavad Gita 1-10

aparyaptam tadasmaakam balaM bheeShmaabhirakShitam

paryaptam twidamEtEShaaM balaM bheemaabhirakShitam ||10||

"The strength of our army which is protected by Bhishma is immeasurable where as that of Pandavas protected by Bheema is measurable.”

There are different meanings attributed to aparyaptam and paryaptam. If we take the meaning of aparyaptam as immeasurable and paryaptam as limited or measurable then he was trying to encourage everybody on his side and was conveying that he would win the war. It is always advantageous to be on the winning side due to the benefits one would derive after the war. If aparyaptam meant insufficient as some have been trying to analyze it means that Duryodhana was specifically trying to woo Dronacharya. Bhishma had a soft corner towards Pandavas and was also older than Dronacharya. Bhishma would not be able to fight this war to his fullest capacity. So the onus to win the war was on Dronacharya who was next in line to become the CIC. Thus highlighting the importance he was satisfying the ego of Dronacharya.

One more important thing to observe is that the he says Pandavas army was protected by Bhima, even though Drishtadyumna was the CIC of Pandavas army. Since the childhood Duryodhana wanted to eliminate Bhima, but Bhima survived every assault. Bhima was at the center of his thoughts. He was his main opponent. If we look at Mahabharata closely, the real hero would be Bhima and not Arjuna as the main villains - Duryodhana and all his brothers were killed by Bhima. Duryodhana's fear about Bhima is only legitimate.