First skirmish at the Cave

The first skirmish of horcrux cave was when Regulus Black and kreacher tried to get the locket and Regulus Black drank the potion and put in a fake locket with a note to the Dark Lord.

Background imformation
Lord voldemort asked for a house elf and Regulus gave Kreacher. Lord Voldemort made kreacher drink the drink and it caused Kreacher feel pain and to see things he didn't want to see. Lord Voldmort left Kreacher to die on the island either of thirst or to get pulled into the water by the inferi. He could apparated back because Voldemort didn't take into consideration house elf magic.

Regulus found out about his horcruxes and knew there were more. He asked Kreacher to take him back.

The skirmish
Regulus drank the potion because he did not fear pain or death. He put in a fake locket with a note to the dark lord. He asked Kreacher to leave him to die and he jumped into the water and the inferi pulled him down.

Appearances

 * Harry Potter and the Deathly Hallows