Why did England get involved i n world war 2?

England got involved in World War II primarily due to its commitment to defend Poland after Germany invaded the country on September 1, 1939. Britain had pledged support to Poland and issued an ultimatum to Germany, demanding a withdrawal of troops. When Germany ignored this ultimatum, Britain declared war on Germany on September 3, 1939. Additionally, the rise of fascism and aggressive expansion by Nazi Germany posed a significant threat to European stability and security, prompting Britain to act.