Simplify the following text for a Grade 7 native English-speaking person.
Original: The Iron Cross of the Second World War was divided into three main series of decorations with an intermediate category , the Knight 's Cross , instituted between the lowest , the Iron Cross , and the highest , the Grand Cross .
Simplified: During the Second World War an extra type of Iron Cross medal was given . It was the Knight 's Cross of the Iron Cross and was given for acts of extreme battlefield bravery or successful leadership .