The marches in the cities of Nice, Pau, Nantes and Orleans were a taste of what was to come in Paris today, where a huge rally will be held for national unity, to be attended by President Francois Hollande and two dozen world leaders including Germany’s Angela Merkel, Britain’s David Cameron and Italy’s Matteo Renzi. Arab League representatives and some Muslim African leaders as well as Turkish Prime Minister Ahmet Davutoglu will also attend.