The famous statement of the early IRA was that “we can achieve an independent Irish republic by behaving as if it exists already”.
The head of the Irish Republican Brotherhood at the time, Eamon De Valera said, “we defeat the British Empire by ignoring it.”
That meant the complete refusal to recognize British institutions, to ignore, as much as possible, the presence of the occupation. It meant the establishment of Irish institutions, courts, schools, and so on, so that the people would not refer any matter to the British, and instead deal exclusively with parallel Irish institutions.
This is a necessary component of any independence movement; creating an alternate system of order by which you can marginalize the imperial system from the daily lives of the population as much as possible.