The Gita is structured as a dialog between God and Arjun. The first chapter describes Arjun on the battlefield facing his enemies. Earlier, both he and his opponents called upon Lord Krishna for help. Krishna offers his entire army to one side and Himself as charioteer to the other. Arjun chooses Lord Krishna.
But even with God by his side, Arjun feels dejected and filled with doubt. His mind starts spinning. He sees his wise old uncle, his teacher, and his cousins facing him and he cannot make himself fight:
How, Krishna, can I fight Bhishma and Drona with arrows on the battlefield?
I respect them.
It is better to live as a beggar, but without killing,
Because after killing them
Our hands will be stained with their red blood.
Lord Krishna’s response is the Gita. After hearing God’s word, after receiving God’s answers to his many questions, and after seeing God’s powers, Arjun is both humbled and strengthened. He no longer doubts or fears. He finds faith and courage. He stands ready to fulfill his duty as a warrior and to fight for his honor:
Because of your mercy
I know the Truth.
I will be firm and do what you wish.