Some of them were in charge of protecting Hogsmeade and Hogwarts. What were the rest of them doing to aid in bringing down Voldemort and his Death Eaters? What were they doing during the events of the Deathly Hallows, when the trio was horcrux hunting? They were probably trying to keep each other safe, and the rest of the world informed through "Potterwatch". But how were they plotting or fighting to bring down Voldemort? Especially since they had no clue what Harry, Ron, or Hermione were up to.
- McGonagall - was at Hogwarts, keeping students safe
- Fleur Delacour - was probably keeping an eye out for the three, but was also (I think) abroad
- Snape - was at Hogwarts, double-agent-ing
- Hestia Jones - since she took the Dursleys away, was probably watching out for them
- Shacklebolt - PM's bodyguard
- Tonks - Not sure
- Arthur Weasley - Not sure
- Bill Weasley - Order rep to the Goblins
- Charlie Weasley - Recruiting from abroad
- Molly - taking care of the order as they used/ransacked her house for secret work
- Fred/George - Not sure
For the "Not sure" - I assume, at least some of them were out looking for the three (Harry, Hermione, Ron), and/or smuggling information/items for the Order
- Most of what I've posted is from here (apologies for not crediting correctly the first time round). For the last little bit ("not sure"), that's more what I think would be happening/would hope, but cannot say for sure.
There is not much information as to what the Order was doing during Half-Blood Prince. There are, however, two "missions" that we definitely know about:
- Spying on Werewolves
When Harry talks to Lupin over Christmas, we have the following dialogue:
“What have you been up to lately?” Harry asked Lupin, as Mr. Weasley bustled off to fetch the eggnog, and everybody else stretched and broke into conversation.
“Oh, I’ve been underground,” said Lupin. “Almost literally. That’s why I haven’t been able to write, Harry; sending letters to you would have been something of a giveaway.”
“What do you mean?”
“I’ve been living among my fellows, my equals,” said Lupin. “Werewolves,” he added, at Harry’s look of incomprehension. “Nearly all of them are on Voldemort’s side. Dumbledore wanted a spy and here I was… ready-made.”
He sounded a little bitter, and perhaps realized it, for he smiled more warmly as he went on, “I am not complaining; it is necessary work and who can do it better than I? However, it has been difficult gaining their trust. I bear the unmistakable signs of having tried to live among wizards, you see, whereas they have shunned normal society and live on the margins, stealing—and sometimes killing—to eat.”
- Protecting Hogwarts
When Dumbledore leaves Hogwarts he has several Order members come to protect it. As Dumbledore tells Harry immediately before they set out to find the Horcrux:
"Do you think that I have once left the school unprotected during my absences this year? I have not. Tonight, when I leave, there will again be additional protection in place.
And as McGonagall elaborates after the battle (my emphasis):
"I don't know exactly how it happened," said Professor McGonagall distractedly. "It's all so confusing.... Dumbledore had told us that he would be leaving the school for a few hours and that we were to patrol the corridors just in case... Remus, Bill, and Nymphadora were to join us... and so we patrolled.