Complex sentence: About 500 tanks and self-propelled guns from nine tank brigades of the 5th Guards Tank Army attacked the German positions in two massive waves, with 430 tanks in the first echelon and 70 more in the second.
Split into simpler sentences: About 500 tanks and self-propelled guns from nine tank brigades of the 5th Guards Tank Army attacked the German positions. They attacked in two massive waves, with 430 tanks in the first echelon and 70 more in the second.