The video below shows a darner attacking a pair of meadowhawks. They escaped, and after a brief rest were able to resume egg laying as before.
The video also shows the interesting way that Autumn Meadowhawks lay their eggs. First, they dip the female's abdomen into the water. When they rise a droplet of water is attached to the end of her abdomen, and the pair then hovers for several seconds as she lays eggs into the droplet. Now, how do they dislodge the water droplet to deposit the eggs into the vegetation? Very simple – they swoop down and slam into the vegetation, giving the female a good "whack." If I were ever to be reincarnated, I would not want to come back as a female Autumn Meadowhawk.