4th Army
... that the disintegration of the Royal Yugoslav 4th Army during the Invasion of Yugoslavia in April 1941 was caused largely by fifth column activity?
... that the disintegration of the Royal Yugoslav <b id="mw7A"><a href="./4th_Army_(Kingdom_of_Yugoslavia)" id="mw7Q" rel="mw:WikiLink" title="4th Army (Kingdom of Yugoslavia)">4th Army</a></b> during the <a href="./Invasion_of_Yugoslavia" id="mw7g" rel="mw:WikiLink" title="Invasion of Yugoslavia">Invasion of Yugoslavia in April 1941</a> was caused largely by <a href="./Fifth_column" id="mw7w" rel="mw:WikiLink" title="Fifth column">fifth column</a> activity?