They were not legally required to follow Britain, but they absolutely followed Britain anyway. If Britain has sat out the war, Canada would have sat out the war. If Britain had joined the axis, Canada would have joined the axis.

Both King and Opposition Leader Robert James Manion stated their opposition to conscripting troops for overseas service in March 1939. Nonetheless, King had not changed his view of 1923 that Canada would participate in a war by the Empire whether or not the United States did.

It had been clear that Canada would elect to participate in the war before the invasion of Poland on 1 September 1939. Four days after the United Kingdom had declared war on 3 September 1939, Parliament was called in special session and both King and Manion stated their support for Canada following Britain, but did not declare war immediately, partly to show that Canada was joining out of her own initiative and was not obligated to go to war.