Bhagavad-Gita: Chapter 1, Verse 19

Rudra Vaisnava Sampradaya:

Visnuswami

Sridhara Swami's Commentary

The uproarious sound of the Pandavas conch shells being blown caused great fear to the sons of Dhritarastra. This is what this verse means. How? By its power, by its power it made the heavens and the earth resound, filling them all with its reverberations.

Brahma Vaisnava Sampradaya:

Madhvacarya
There is no commentary for this verse.

Sri Vaisnava Sampradaya:

Ramanuja

Ramanuja's Commentary

Duryodhana while witnessing the strength of the Pandavas army supported by the might of Bhima weighed his own armies strength under the command of Bhishma and perceiving the mood of his perceptor Dronacarya, he could understand the inadequacy in his own troops and the perfection of strength on the Pandavas side to be victorious and internally this aggrieved him heavily. Bhishma seeing all this gave a roar like a lion and blew a mighty, reverberating blast on his conchshell which was followed by a tumultous beating of drums, blaring of horns and blasting of conchshells as if indicative of the victory in order to cheer up Duryodhana. Immeadiately upon hearing this Lord Krishna and Arjuna seated in their majestic chariot capable of conquering all the worlds; both seized their conchshells and reverberated a sound that shook all the worlds. Thereafter Bhima, Yudhisthira, Nakula and Sahadeva and the rest of the maha-rathas of the Pandava army blew their conchshells and the roar which was heard cleaved the hearts of Duryodhana and the army of the Kauravas and in their hearts they felt that the battle was already lost. Thus did Sanjaya narrate to Dhritarashtra whose only concern was for the success of his son Duryodhana and the Kauravas in the battle.

Kumara Vaisnava Sampradaya:

Nimbaditya

Kesava Kasmiri's Commentary

Another source of fear for Duryodhana is indicated by the description of how the tumultuous blasts of the mighty warriors of the Pandava army sounding their conchshells shattered the hearts of Duryodhana's army the Kauravas. Shattering the heart means the sound created excruciating pain within their hearts due to its volatile nature. How was this accomplished? By the violent force contained within the blasts which reverberating, filled the earth and the sky with echoes.