The 501st legion was a group of clones set out (with Darth Vader) to destroy all jedi in the jedi temple, after sucedeng their mission they wated for the other jedi to respond to the hologram saying all jedi report to the jedi temple emeidietly. Meanwhile Yoda and Obi-Wan went over to reverse the message and were met by the 501st legion. Obi-Wan and Yoda destroyed the rest of the legion (who did not get killed by the jedi in the temple).
Response to anyone who asks if they can use my decal: Yes you can but if you post it on mocpages or something you have to give me credit.(this goes for all my decals)