This is the day that Fireheart is leading ThunderClan to conquer Tigerstar's dog pack. Fireheart chose Graystripe to go on the patrol:
Graystripe blinked and sat up. "This is just like the old days," he mewed, in a vain attempt to sound cheerful. "You and me, charging into danger again," He pushed his forehead against Fireheart's shoulder. "Thanks for choosing me, Fireheart. I'm scared stiff, but I'll prove I'm loyal to ThunderClan, I promise."

I love Graystripe so much, it hurts.

From The Prophecies Begin #5: A Dangerous Path