My feelings have always been that the argies seemed to think that the Brits would not be able to respond militarily to their seizure of the Islands. The RAF only had a single aircraft which could even reach the South Atlantic. The Argies had air superiority and seemed to have counted on control of the seas around the Falklands and had already landed troops and dug in.
After the invasion the heads of the army and RAF told Margret Thatcher at cabinet that there were no options to retake the Islands. It was the first sea lord Sir Henry Leach who walked in and told them the Navy could do it even though the government had just agreed to drop the axe on the navy big time. I think that they took a massive gamble by attempting it though. The biggest obstacle of all was the weather. If you look at the Falklands on a map they are not much further north than the Antarctic circle, the seas in the South Atlantic in winter are awful. They had an increasingly shortening window to act. Ships which the Royal Navy needed were in mothballs. A lot of what they were going to fight the conflict with was untested. It all had to be thrown together in 2 weeks and sent. If it was ready or not.
At the time the British armed forces were mainly dealing with the peacekeeping mission in Northern Ireland and preparing to fight the third world war against the Soviet Union. The argentine armed forces were a reasonably professional outfit that had benefited from a lot of western military equipment. Some of the same arms manufacturers who supplied equipment to the Brits had also supplied stuff to the argies. It caused a whole series of frantic back room preparations and fact finding that needed to be done in a matter of weeks.
I've always been of the opinion it was their war to loose.
The sinking of the Belgrano for example. The Argentine Navy had embarked on this operation but seemed to have no preparedness for anti submarine warfare despite the fact they should have known the Brits would employ them. They then scampered back to port making the Royal Navy's job even easier. Then after the black buck raid the argies pulled their airforces posture to defend the mainland. Which meant that their jets traveling from the mainland only had 10-15 minutes loiter time over the battlefield. Their pilots despite being skilled were extremely nervous and loosed off their exocet missiles at the first targets on their radar instead of trying to sink the carriers.
Likewise on East Falkland the ground forces there basically just sat behind fortifications on East Falkland around Port Stanley. I actually worked with a guy who served in the army and was on the Falklands just a little after the war. He says Port Stanley is surrounded by mountains and he could never understood why they dug in there and waited. Again. A complete lack of aggressiveness on the part of the officer corps. They literally surrounded themselves and waited for a highly competent professional army with a large number of elite troops to encircle and smash them instead of trying to meet them on more favorable battlefield nearer the landing grounds.
The argies despite being reasonably professional seemed to lack the kind of aggressiveness needed to win, they had even sent conscript soldiers to fight in a war without even bothering to supply them with enough winter clothes. They also made a series of fatal tactical mistakes. Mistakes are inherent to war fighting. The Brits made a few. The argies made more. Wars are won and lost on that.
The conflict probably wouldn't have happened if the Navy had kept the HMS Ark Royal in service. The Ark Royal probably could have destroyed the argentine air force outright in about 5-6 days. The Royal Navy would have had total air dominance over the Falklands and Argentina.
