Online description of Bandidos Operation;
"Los Bandidos Operation is one of the larger extra activities available in the game. These are text-based missions where you have to make various choices on the game board, and each will have a percentage chance of success. You can start this operation by interacting with Los Bandidos boards".
You find the Bandidos board in a Guerilla camp if you have built the Bandidos Barracks at the Foreman. You need to have at least one Banditos Leader. You also need banditos which you gain by freeing detainees, hijacking prisoner transports, helping the people of Yara etc.
Simply complete 5 Banditos operation and the achievement will unlock.
The Operation needs to be a success. Sometimes you will lack the requirements to finish an operation, and it will not count.
The shortest operation is one hour. When the operation is complete a notification will appear calling you back to the Banditos board. You can run several operations at the same time, speeding up the process.