I see how my children really appreciate a parent that stands up for them. The playground can sometimes turn into a bully-ground too. I've seen how older kids dominate the swings, not letting anyone else have a turn even though they've been asked politely. KokoD came crying home one day when the other kids had told him to get off the swing. Once again, the kids looked to us to stand up for them, protect them, and to seek justice. Their father accompanied them the next few days and it was funny how when it was time to leave, kokoD insisted they wait for "everyone" to be at the playground first. Sort of like, "my father is here, see if they dare to disturb me."
As for me, I need to learn to be a bit more aggressive. Sometimes, I'm too "chicken" to fight for them. I'm more of the "let's walk away" type. But once in a while, I think our children need to see that their parents will fight for them, that you can be their shield. Especially when others have wronged them. I'm glad my DH has stepped up to that role.