Complex sentence: Schneider-Creusot or Schneider et Cie began as an iron and steel maker and developed into a major French arms manufacturer, so it was natural that their first aircraft design was a large night bomber with an all-metal structure.
Split into simpler sentences: Schneider-Creusot or Schneider et Cie began as an iron and steel maker and developed into a major French arms manufacturer. It was natural that their first aircraft design was a large night bomber with an all-metal structure.