Why did Sarawakean warrior named rentap able to beat the British countless times?

by Iplayhexaria

How did Rentap a Sarawakean warrior that fought against the white rajahs (Brooke family) and he beat the world's most professional army at the time? How did he do it? What tactics did he use?

Iplayhexaria

Whoops it was suppose to be how did Sarawakean warrior.