Garp viewed Ace just like his second grandson. He loved Ace as much as he loves Luffy. But somehow it seems to me that his sense of duty to marines are greater than his love for his grandsons. Ace was in the danger of being executed multiple times, and Garp was next to him, but he never tried to save him. He did show discomfort at the idea of Ace dying, but he wouldn't still try to save him. He even got in front of Luffy from saving Ace, even though his love for them was too much and he lost the fight on purpose. So why do you guys think Garp sees his loyalty to marines greater than his love for his grandsons?