to be in a strong position in an argument, etc. because you know the facts :
Everyone agreed with me, so I knew I was on firm ground.
to be in a strong position in an argument, etc. because you know the facts :
Everyone agreed with me, so I knew I was on firm ground.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005