5. LUIS CARRERO BLANCO
The assassination of Luis Carrero Blanco was one of the most audacious and error-laden plots of all time. A group of four commandos decided to killer the Prime Minister when it became clear he was to take over for the Spanish dictator Francisco Franco in 1973, though, their plans did not exactly work out.
The first part saw them successfully managing to convince a landlord that they were art students, giving them the chance to rent a basement apartment. From there, they began to dig a tunnel under a road without any experience or knowledge of tunneling. This caused huge problems as the tunnel kept collapsing and noxious fumes were released from nearby sewage. These problems, combined with the inadequate equipment they were using, meant that it took far longer than they had ever imagined to complete the task.
Ultimately, the plot worked when they were able to blow up the car carrying the politician when he passed over the explosives that had been placed in the tunnel. The explosion had so much force that it sent the vehicle five stories high.