The Archbishop of York embarked on a weeklong fast and prayer vigil for the suffering world on Sunday.
During his vigil of Hope and Trust for the Peace of the World, Dr John Sentamu will be praying on the hour every hour from 6am to 6pm until Sunday 31 August.
He will be saying three Kyrie Eleison (Lord Have Mercy) in succession, followed by the Lord's Prayer, and repeating the cycle three times.
The Archbishop is inviting others to join him in saying prayers for people in communities affected by militarism, idolatry, dictatorships and poverty.
As a mark of solidarity he is displaying a piece of white linen above the door to the St John's Chapel at York Minster.
He is asking others to place a piece of white linen in their windows as a symbol of peace.
He said: "Dearly beloved Disciples of Jesus Christ, wherever you are in the world, I beseech you, in the Name of our Lord, to join me in heart and mind for seven days of prayer and fasting for peace and justice in God's World.
"Please join me in praying especially for those places in our global village devastated by militarism, idolatry (the worship of God wrongly conceived), dictatorships and abject poverty.
"One way of making our solidarity and commitment together to be instruments and makers of peace is to place white linen in our windows. All people of good will may do this! Be the change you want to see."