The final moments of the King of Israel reveal a profound act of bravery, as he chooses to sacrifice his own life in the midst of a raging battle to save his army from defeat.
As the fighting unfolded, the primary approach among commentators is that the conflict steadily intensified, swelling like rising floodwaters as the two armies clashed with immense force. However, another perspective suggests that the Israelites actually held the upper hand and were succeeding in the fight [מלבי״ם]. This success was possible because the soldiers remained completely unaware of their king's severe injury. The battle simply continued its normal course, even though the king was no longer capable of actively participating in the combat [ביאור שטיינזלץ].
Despite his critical wound and a complete lack of medical attention, the king displayed extraordinary courage. He refused to abandon the front lines and would not even allow himself to bend over from the pain. Instead, he forced himself to endure the agony, remaining standing upright in his chariot to face the Aramean army alongside his warriors. He did this specifically to hide his condition from the Israelite troops. He knew that if they saw him fall, they would lose heart and run away, and the beginning of any military collapse is the initial retreat [רש״י].
Ultimately, the king paid for his steadfastness with his life. He died that evening from massive blood loss [ביאור שטיינזלץ]. As he stood his ground, the blood flowed continuously from his wound, pouring downward into the deep, middle section of the chariot until the enclosed space was entirely filled with his blood.