Ole Petey might need an ELI5 guide to Signal.
Signal's a great app to keep your communications secure, but make sure you know the identities of the users in your group chats.
Our SSD guide on how to use Signal includes guidance on managing your group chat preferences. https://ssd.eff.org/module/how-to-use-signal#manage-your-group-chat-preferences
Discussion
I'm embarrassed to ask at this point, but what did I miss?
The director of the Pentagon DMed war targets and plans to someone that should not have gotten them hours before the attack. He included him in on a group chat by accident.