Can someone explain which episode Haki was first used in?

Im not 100% sure but I think it was when Luffy battled the Gorgon sisters -.-

Haki ou "Ambtion" was actually introdouced in the first episode where shanks Lost his arm he used Haoshoku Haki. Now there are three type of Haki


Kenbunshoku Haki-witch allows some one to sense other people ou on coming attacks

Busoshoku Haki - This Haki allows the user to harden himself ou to stregthen ones moves.

The final form of Haki is called Haoshoku Haki this cannot be learned but rather "unlocked" par the user. The person can knock out ou strike fear into people par simply looking at them.

In the Manga, Haki was introduced in the first chapter. However in the animé they decided to déplacer the flashback of seven an old Luffy to episode four. So, in the animé they first introduce Haki in episode 4. Although we don't know that it is Haki, it is used par Shanks when he uses Haoshoku Haki against the Sea King that was attacking Luffy. HAki wasn't brought back until episode 151 in which Shanks, once again, uses Haoshoku Haki. This time against Whitebeard's crew. Haki is then brought back once plus in the Skypia ar. Only this time it is Kenbunshoku Haki, but is referred to as Mantra. Haki then doesn't come back until the Sabaody Archipelago arc, where it is used par Rayleigh. after this, Haki becomes a magor factor in the series, being use par Rayleigh, Sentomaru, the Kuja Pirates, Luffy himself and many others. It continues to be used without the audience knowing exactly what it is until Rayleigh's explanation of it in episode 516.

I am pretty sure that on Sky Island, what is explained as Mantra can infact be seen as a form of Observation Haki, but the first time it was used i when Shanks saves Luffy, looses an arm, And then uses Conqueror Haki to scare away the Sea creature.