Jack isn't immune to wounds, he can still be hurt, he just can die. You can see him with scratches in past episodes. Although it is likely he can heal faster. Elbalug 10:54, 3 February 2008 (UTC)
Jack should know about the details of tommy, he was working for torchwood in 1918, they knew he was immortal, so, they could have told him the details then. – The preceding unsigned comment was added by 188.8.131.52 (talk).
Jack was working closely with Torchwood by this time, but not for. To put this in perspective, he didn't become leader of Torchwood 3 until around the turn of the century, and it's unlikely it took him 100 years to take such a job unless he wasn't in their full employ. Danochy ☎ 14:07, August 31, 2018 (UTC)