Wilson's supporters were lined up for a favorable ratification vote, but were unprepared to act unless he authorized them to accept mild qualifying language, this he refused to do.
I cannot understand the meaning of he authorized them to accept mild qualifying language, this he refused to do. What does it mean?
First of all, here's how i believe this sentence would appear with the correct punctuation:
"Wilson's supporters were lined up for a favorable ratification vote, but were unprepared to act unless he authorized them to accept mild qualifying language; this he refused to do."
Putting "; this he refused to do" at the end is like saying
"... accept mild qualifying language. He refused to do this."
Does that help? It's not clear from your question exactly what you're having problems with.
Mild Qualifying language are extra terms that define how a ratification is applied. Mild suggests they are only small changes.
For example, say you were ratifying:
Cyclists will be able to ride their bicycles in bus lanes in our city
Mild qualifying language would, for example, change it to:
Cyclists on road bikes would be able to ride their bicycles in bus lanes in our city
