A lot of people see the presence of the kingsguards at the Tower of Joy as the proof that R+L=J is true, but I think that´s not true. I believe we can be sure that the KG were at the Tower of Joy because Rhaegar told them to do so; the problem is why did they stayed there once Rhaegar and Aerys were dead, instead of joining Darry, Vyserys and Daenerys? Why did they fight Ned and company?. Most people are quick to accept the theory that they were there to protect Aergon´s heir (baby Jon),