@General:
At least Dr. Hiriluk had the courage to try and save his country and was able to save his son, unlike a certain marine who couldn't even be bothered to try and save his grandson, the coward.
I recall Garp put family over duty the moment he let Luffy punch him off the makeshift bridge to reach Ace. Instead of squashing him like a bug which he could have very well done. Ace wasn't even his grandson but he risked his position by letting letting Luffy reach and free him. What's so cowardly about taking a hit so Ace could be set free?
As for Luffy he had all the help he needed and he managed to escape alive. Anyone can tell Garp is no coward and he cares for Luffy and cared for Ace.
@zullzero:
Garp sucks. He didn't want his kids to be what they wanted to be, he wanted them to squash their dreams and be footsoldiers for the WG. Just so the WG wouldn't hunt them down for being the children of their enemies. Yeah, he was trying to look out for them, but he certainly didn't want them to live their lives to their fullest. Hiriluk was all about Chopper getting out on the ocean and living the best life he could.
Wanting your children to become upright citizens of the world and not rogue pirates doesn't mean he didn't want them to live their lives to the fullest. Marines can't live their lives to the fullest? Garp was looking out for the safety and well being of Ace and Luffy. That's why he trained them so hard. That's what it all comes down to.