Catholicism and Peacemaking
Explore links to key Papal and Vatican Documents on Catholic Social Teaching at the USCCB website. Key among them with regard to peace is Pacem in Terris.
Consider key insights in the Catechism of the Catholic Church, notably Part Three: Life in Christ. Section 2: The Ten Commandments. Chapter 2: "You shall love your neighbor as yourself." Article 5: The Fifth Commandment: You shall not kill.
CatholicCulture.org offers a succinct page of the Catechism.
Visit the Vatican Website, Curia, for the Pontifical Council for Justice and Peace.
Consider the term 'peace' in a broad sense by Catholic Answers at A Primer on Peace.