Complex sentence: In 1934, the Bears played a 13--0--0 regular season and became the first NFL team to complete an undefeated regular season without tied games, but lost the 1934 NFL Championship Game against the New York Giants.
Split into simpler sentences: In 1934, the Bears played a 13--0--0 regular season and became the first NFL team to complete an undefeated regular season without tied games. However, the Bears lost the 1934 NFL Championship Game against the New York Giants.