Complex sentence: Eventually she was assigned to the Armed Forces' National Hospital where she served as a Dentist for many years whilst in service at this hospital she was promoted to Capitan, Major and Leutenant Colonel.
Split into simpler sentences: Eventually she was assigned to the Armed Forces' National Hospital where she served as a Dentist for many years. Whilst in service at this hospital she was promoted to Capitan, Major and Leutenant Colonel.