Simplify the following text for a Grade 7 native English-speaking person.
Original: On 30 May 1923 , the IRA 's new Chief of Staff Frank Aiken ( Lynch had been killed ) called a ceasefire and ordered volunteers to `` dump arms '' .
Simplified: When the IRA 's new Chief of Staff called a ceasefire Frank Aiken on 30 May 1923 the government had won .