The story
See green-ink brigade.
Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: A letter written to a newspaper editor, politician, etc., expressing eccentric views; such a letter is often stereotyped as being handwritten in green ink, characterized by the frequent use of capital letters and underlining, and lengthy. Full definition →
See green-ink brigade.
Etymology from Wiktionary, CC BY-SA 4.0.