He was fearless in defending the weak - young or old - against the powerful, and he founded several religious institutions including the Daughters of Saint Mary of Providence and the Servants of Charity to work with the poor across the world. He also founded the Pious Union of St Joseph, whose first member was Pope Pius X.
Although God guided his life in another direction, he retained his devotion to Don Bosco, which can be seen in a prayer he wrote in his monthly magazine, Divine Providence, in 1908: 'May the great soul of John Bosco, who from on high protects the Congregation of his sons the Salesians, now too numerous to count, be pleased to turn his gaze on the Institutes of Divine Providence and extend the kindness of his protection on all those who belong to these works and especially on his devoted admirer and student, Fr. Louis Guanella.'
His older sister, who was his housekeeper in his days as a parish priest, was the Servant of God Caterina Guanella.
St Louis was canonised in 2011 by Pope Benedict XVI.