Justify Anglicanism in the face of Catholics and Orthodox.
Also Anglican General
Anglican orders are valid.
If Anglican Orders are invalid, then neither are post-Vatican II Catholic orders, and the only Bishops currently valid are the SSPX Bishops.
The removal of language on sacrifice and propitiation in the Anglican ordination rites, as critiqued by Pope Leo XIII, were done in the Catholic Ordination rites after Vatican II. The same is true of the stripping of the altars, which took place both in the Anglican world post-reformation, and in the Catholic world post-Vatican II. All of this to say that either the Anglican church is legitimate, or the postconciliar Roman Catholic church is illegitimate.
For the criticism of Anglican Orders see Apostolicae Curae: http://www.papalencyclicals.net/leo13/l13curae.htm
For the way these criticisms boomerang on the Catholic Church see Michael W. Davies Order of Melchesidek:
http://www.catholictradition.org/Eucharist/melchisedech.htm#CONTENTS
Christianity in the British Isles was Historically separate from Rome
Christianity in the British Isles comes from the Celts.
The Celtic Christianity came from Syrian Christianity.
After the Romans left Britannia, the Christianity that took the place was Celtic Christianity.
Even after the Celts were brought in communion with Rome, their own peculiar eccelesiology remained, focused primarily around monastic communities and abbots, rather than bishops and lay priests.
The rule of the English church was reverted to Norman Bishops by William the Conqueror, however, the Normans became English, resulting in 500 years of English Catholicism as it existed during that period
The structure of a Monarch ruling the church dates back, not to Henry VIII, but to William the Conqueror, who reformed and unified the English Church, replacing uncooperative bishops and clergy as he saw fit. This was with Rome's approval, of course. But it was the monarch who was at the top of the hierarchy of England's church, even though it was officially the Pope.
See: https://www.lagrange.edu/resources/pdf/citations/2016/25_Shirley_History.pdf
The Anglican Church has legitimate jurisdiction over the United States
The majority of the signers of the Declaration of Independence were Anglican
The majority of those at the Consitutional Convention were Anglican.
We hold funerals for heads of state in the National Cathedral of the Episcopal Church.
The current state of the country reflects the current state of this church. (I can't prove this one, but think about it.)