Simplify the following text for a Grade 10 native English-speaking person.
Original: In 1971 , he initiated a political power struggle that led , with Soviet support , to his becoming the new leader , replacing Walter Ulbricht as First Secretary of the SED Central Committee and as chairman of the National Defense Council .
Simplified: In 1971 , he started a political power struggle . The Soviet 's supported him , so Hoinecker became the new leader , or General Secretary , of the Socialist Unity Party , replacing Walter Ulbricht .