I know that Hitler has a reputation for trying to be very hands on, and is often blamed for notable setbacks experienced by Germany as a result. Also that Stalin kept a very close eyes on military matters, although the USSR propaganda machine might mask just what was his own touches and what are merely credited.
But how much did their Western counterparts stick their noses into strictly military affairs?
Did they mostly keep to the larger strategic picture, or were they ever trying to dictate tactical matters?
Did they cause any setbacks or defeats because of their meddling?
Mainly interested in the Big Two, but I if there is anything to be said for King, or for the myriad of Australian PMs, that is welcome as well.
Yes, two decisions made by Churchill which had detrimental to the war effort was
The decision to intervene in Greece in 1941 when Germany invaded which resulted in the defeat of Commonwealth forces there. Not only that, but it quite possibly derived Wavell of the reserves he needed to finish off the Libyan campaign which could have averted the North African theater against Afrika Korp altogether.
The decision to send the Repulse and the Prince of Wales to the far east in an effort to deter Japanese aggression in the region. Unfortunately, Churchill had an under-informed and over-optimistic view on the power of battleships in an era of naval aviation. The net result was to be the loss of both capital ships to Japanese airpower and the death of their commander, Admiral Tom Philips and was considered to be one of the worst British disaster of the war.
Roosevelt was pretty much hands off. His military staff (primarily General Marshall and Admiral King) were key people who essentially ran the war for him. He set some basic conditions, such as a Germany first principle.
Churchill, however, did have a tendency to stick his nose in. Some areas where he interfered to the detriment of the cause were:
Committed the allies to invading Italy in 1943 followed by a long slog up the peninsula. While this did induce Italy to surrender, the mountainous terrain was quickly occupied by a few German divisions who made the allies pay for each mile.
Moving forces from North Africa to assist Greece against a possible invasion by German forces. The force sent to Greece was too small to effectively help when the attack happened. With those units the allies would likely have defeated Italy in North Africa in early 1941.
Shelling of the French Fleet at Mers-el-Kébir and Dakar to prevent them being seized by the Germans. This was just inexcusable and was ordered over the heads of most of the Royal Navy chiefs.
Some things he had to be talked out of or narrowly avoided disaster:
Churchill wanted to land in the Balkans rather than northern France in 1944. Again this would have forced allied forces to fight through easily defensible terrain half a world away from their real objective (Germany).
Invading Norway in 1940. This was so close to disaster I shudder to think about it. Germany invaded Norway in April 1940 to secure a supply of iron ore from Sweden. Allied troops quickly arrived to support Norway. Quickly, because they were already preparing for their own invasion. Which would almost certainly have fizzled on the beaches and forced the Norwegian government to actually request assistance from Hitler.