How did Richard the Lionheart become King?

Richard became King when both his eldest brothers, Henry 111 (King of England) and Geoffrey (Duke of Brittany) died. All of these three siblings took down their father King Henry 11 so that Henry 111 can become king. After Henry111 died Geoffrey took over but when he died, Richard was the only one left and became King known as King Richard 1 or King Richard the Lionheart.