The following is a Patronus from Dumbledore sent to all Order members:
Given the recent pardons the Ministry has seen fit to issue, I wish for you all to be present in Hogsmeade this Saturday, while the students of Hogwarts are enjoying their time in the town. Keep your eyes open and be on guard at all times, but do not broadcast why you are there. There is no reason to stand guard, but do be aware of your surroundings and any possible threats.
If you see a Death Eater, send me and the others a Patronus immediately. I will arrive and assess the situation. If needed, I may ask you all to help escort the students back to the castle.