Assisi - Pope Francis travelled to the Italian town of Assisi on Thursday for a private visit to mark the 800th anniversary of the "Pardon of Assisi", under which the slates of sinners can be wiped clean.The 79-year-old pope arrived by helicopter in the hill-town in central Italy where his namesake Saint Francis of Assisi was born and found God, renouncing his wealth for a life of poverty and becoming an emissary of peace during the Crusades.The Argentine pontiff, who took the name of Francis in homage to the famous Christian friar and his devotion to the downtrodden, prayed in silence in the Porziuncola, a tiny church inside the Basilica of Saint Mary of the Angels.It was here the Franciscan movement was founded, and here the venerated patron saint of Italy, animals and the environment died.On Wednesday the pope said it would be "a very simple pilgrimage, but a very significant one". Thousands of pilgrims turned out to catch a glimpse of the head of the world's 1.2 billion Roman Catholics, despite the baking heat in the Umbrian town.Born in 1181 to wealthy silk merchant, Saint Francis fought as a soldier and was imprisoned for a year, a period in which he is believed to have discovered God. He famously discarded his riches, was disowned by his father and tended to the poor in rags.Aged 26 Francis said Jesus came to him in a vision and told him three times, "go and repair my house which is falling into ruins".Legend has it he was praying in an abandoned chapel at the foot of the Assisi hills at the time, and sold his horse to pay for the repairs to what would become the Porziuncola.'Greater need for pardon' Ever since his election in 2013, Francis, the first pope from Latin America, has modelled himself on the Franciscan, ditching the ermine furs and papal palace of his predecessors and calling for "a poor Church for the poor".After prayers in the fresco and gold-leaf decorated chapel, the pontiff will visit the adjacent convent's infirmary to greet the sick clergy.Francis's trip is to commemorate the 800th anniversary of the "Pardon of Assisi", also called the Porziuncula Indulgence, by which penitent pilgrims who take part in a solemn annual celebration on August 1 and 2 can be forgiven.The tradition was founded by the saint who, it is said, was so moved by God's mercy to him that he pressed the then pope to grant an indulgence.Catholics believe a plenary indulgence means the sins of the repentant are forgiven and that any penance - which in the early Church was sometimes demanded in the form of money - is scratched."This world torn by terrorism, where people no longer understand, where politicians no longer seek the common good, has more need than ever before of mercy and the Assisi pardon," Michael Perry, head of the Franciscan friars, told Vatican Radio.Saint Francis founded the Franciscan order as well as the Order of Poor Ladies, with young noblewoman Clare of Assisi at its head.He later donned diplomatic robes and headed for the Fifth Crusades, where Western European armies flying under the papal flag were trying to recapture Jerusalem by conquering the powerful Muslim dynasty in Egypt - but swapped the sword for words.