Bhagvad-Gita Chapter 1 Sloka 14 TO 15

HARE KRISHNA!
SLOKA 1/14

TATAH SVETAIR HARYAIRYUKTE MAHATI SYANDANE STHITAU

MADHAVA PANDAVASHCHAIVA DIVYAU SHANKHAU PRADAHMATU

MEANING

Simultaneously on the side of Pandavas both Lord Krishna and Arjuna stationed on a great chariot which was being drawn by white horses, blew their transcendental conchshells.

SLOKA 1/15

PANCHJANYAM HRISHIKESHO DEVDATTAM DHANAJAYAH

PAUNDRAM DADHMANU MAHA-SHANKHAM BHIMA-KARMA VRKODRAHA

MEANING

And now Panchjanya the conch shell of  Godhead Lord Krishna was blown by him.Simultaneously Arjuna blew his Devadutta and Bhima the performer of herculean tasks and a voracious eater blew his terrific conch shell Paundra.

Explanation

        In contrast with the conch shell blown by Great Bhishma the conch shells of Lord Krishna and Arjuna are transcendental the sounding of whom indicates that there is no hope of victory on the other side. Also it is said victory was always on the side of Panduputras as the Godhead Lord Krishna was on the side of Pandavas as whenever and wherever Lord Krishna is present Himself the fortune is bound to stay there because Shree  the goddess of fortune never lives alone without her husband Lord Krishna. Besides that the chariot on which both were seated was donated by Agni ( the god of fire). 

         lord Krishna had been named many names like Harshikesh, because he is the owner of all the senbses, as he is living in the heart of all entities direct and control their senses. here on the battlefield of Kurukshetra Lord directly control the senses of Arjuna. As Lord have many names his devotees also may be given many names like Arjuna is named as Dhananjai because he helped his elder brothers in fetching wealth when it was required by the king for making yagna and sacrifices. likewise Bhima is named as Vrakodra as he could eat as voraciously as he could perform the greatest of the greatest tasks.

        Panchjanya is the name of conch shell of Lord Krishna, Devadutta is of Arjuna while Paundra is the name of the conch shell of Bhima. So the conch shells were blown by all of them to infuse the  courage in their warriors and to make the people of other side presume that they were bound to lose the battle.

HARI BOL!