Conversation so far:
What were the European pressure?
The fall of the Liberal government in 1874 meant the repeal campaign stalled. Although the LNA kept the pressure, persuading Liberal MPs to oppose the Contagious Diseases Acts was slow.
When did the pressures come?
December 1874, Butler left for France, Italy and Switzerland, where she met with local pressure groups. March 1875, Butler formed the British and Continental Federation for the Abolition of Prostitution.
What was the white slave trade in the 19th century?
the slave trade of young women and children from England to mainland Europe in 1879.
Why were young women and children traded in Europe in the 19th century?
the law allowed them to become prostitutes at the age of 13
Was Josephine Butler involved in fighting human trafficking?
After playing a minor role in starting an investigation into an accusation of trafficking, Butler became active in the campaign in May 1880.
What did Josephine Butler write to The Shield?
She wrote wrote to The Shield that the official houses of prostitution in Brussels are crowded with English minor girls“

Question: What else did she say?
Self-contained rewrite: What else did Josephine Butler say to The Shield?