You could always trigger one of those cti-type scenarios, where you do indeed come ashore unarmed and get to watch horrified while your fellows are massacred, but enough stealth and cunning allows you to escape the beach area.
Then you have to stay alive, while stealing a weapon, and taking the fight to the enemy. Sabotage installations, steal supplies, all that Resistance stuff, which is presumably what the rebels were planning to do anyway? There weren't enough to tackle the army head-on, were there?
All the time, some kind of Castro-AI script is directing larger & larger forces to hunt you down wherever you last struck. Perhaps ending with an assassination attempt?