LOURDES, France: French security forces are on high alert as thousands of Catholics converge on the shrine of Lourdes for an annual pilgrimage unfolding in the shadow of a string of terror attacks. Each year, tens of thousands flock to the sanctuary in the foothills of the Pyrenees for the Feast of the Assumption on August 15, marking the ascent of the Virgin Mary into Heaven. This year’s pilgrimage comes as Catholics reel from the killing of an elderly French priest on July 26 by two Islamist extremists, who stormed his church in northern France during Mass and slit his throat. Jacques Hamel’s murder came under two weeks after a Tunisian — said by investigators to have become radicalized by online jihadist videos — ploughed a truck into a Bastille Day crowd in the Riviera city of Nice, killing 85 people. Many in France are now leery about attending public gatherings after three large-scale attacks in 18 months. With tourist arrivals in the country plummeting, authorities had worried that the number of visitors to this year’s pilgrimage would be sharply down. But fears of mass cancellations have failed to materialize — and some organizers say there has even been a last-minute surge. Around 25,000 faithful are expected, including mass groups from Italy and Belgium and a delegation of around 200 members of the Eastern Orthodox branch of Christianity.