Complex sentence: From the 1940's Brunswick established a reputation as the powerhouse of the competition remaining undefeated across two seasons in 1928-1930 and winning six premierships in seven seasons from 1939/40 to 1945/46.
Split into simpler sentences: From the 1940's Brunswick established a reputation as the powerhouse of the competition, remaining undefeated across two seasons in 1928/29 and 1929/30. The club went on to win six premierships in seven seasons from 1939/40 to 1945/46.