The combatants went into war as men, 'grim and glad' and returned as children, 'broken and mad'. Explain why?

The combatants went into war as men, ‘grim and glad’ because they had chosen to serve their country by becoming a soldier. They had a great deal of love for their country and wanted to always keep it safe and protected. This love for the country was what encouraged them to join as a soldier. When war was declared, they gladly offered their service; they were excited that finally they would be doing meaningful action for their country. They shouldered the responsibility of protecting the country seriously.

After the war, however, their hearts were shaken with grief and turmoil because they witnessed the death of many people around them including those of their friends and comrades. They are deeply stressed by the events of the war and experience trauma due to the war. The high spirits they had on going to war has extinguished and they feel a deep sense of loss on returning. Overcoming such trauma is not easy for them. Having spent years at the borders, returning to normal life is problematic for them, they have to start anew just like children who are dependent on others for their psychological needs. Their stressful mind which is filled with hatred and anger towards those who sent them to war will need a lot of time to heal.