The crime of betraying one’s government.
"Formerly, the punishment for high Treason was of a most barbarous character…. Women were burnt. A male traitor was dragged or drawn to the place of execution and hanged; but while still alive, he was cut down and disembowelled. His head was then severed from his body which was quartered. The head and quarters, which were at the Kings disposal, were usually exposed in some conspicuous place—the Temple Bar being a favourite spot—after being boiled in salt to prevent putrification and in cumin seed to prevent birds feasting on them
1952: James Avery Joyce: Justice At Work: (this edition Pan 1957) Page 105.
Providing aid and comfort to the enemy.