How did the death of archduke franz ferdinand instigate (urge on) the collapse of peace in europe?

Franz Ferdinand was an Austrian Crown Prince and he was killed in Sarajevo by a Serbian rebel.

Austria demanded of Serbia to allow them to enter Serbia to search for this rebel, which Serbia did not agree on, and Austria declared war on Serbia. In response, Russia declared war on Austria, leading to the war.

Fiscal policy because it refers to the use of government spending and tax policies to influence macroeconomic conditions, including aggregate demand, employment, inflation, and economic growth.