Simplify the following text for a Grade 12 native English-speaking person.
Original: Brigadier-General Reginald Edward Harry Dyer CB ( 9 October 1864 â `` 23 July 1927 ) was a British Indian Army officer responsible for the Jallianwala Bagh massacre in Amritsar ( in the British India province of Punjab ) .
Simplified: Brigadier-General Reginald Edward Harry Dyer CB ( October 9 1864 â `` July 23 1927 ) was a British Indian Army officer responsible for the Jallianwala Bagh massacre .