The 39 Clues Wiki
The 39 Clues Wiki

Captain McIntyre was an English military officer during World War I. His trench was next to Brigadier-General Keswith's trench in France. McIntyre was in command of a tall private and Smitty, among others. Colonel Bullsworth sent Rupert Davenport across no man's land to deliver a message to McIntyre, who in turn used Rupert to send a message back to Bullsworth.

It is unknown if McIntyre was at all connected to the Cahill family, or if he was related to William McIntyre.