Rishi(Saint) Vishwamitra along with his disciples used to worship and do yagna(ritual sacrifices) in the forest but the rakshasas(demons) didn’t allow them to do so. They used to interfere in the sacred rituals and interrupt the sacred processions.
Thus Rishi Vishwamitra went to King Dashratha and asked him to handover his sons; Rama and Lakshmana so that they could put an end to this chaos by killing those merciless demons.
Upon hearing this, King Dashratha grew pale. He was terrified of the fact that his young son who was dearer to him than his own life had to face such deadly demons. He pleaded in front of the Rishi and instead promised him to send his army.
Seeing him being deluded by the love for his son, Rishi Vashishtha approached the King and curbed his delusion. He told him the greatness of Rishi Vishwamitra and finally convinced him to send Rama and Lakshmana along with the great sage.
Upon hearing Rishi Vashishtha, King Dashratha took a sigh of relief and finally handed over his sons to Rishi Vishwamitra. The great Rishi blessed the King and went to the forest along with Rama and Lakshmana to put an end to the demons.