He was one of the very first priests to react to the changes to the Mass and founded the Catholic Traditionalist Movement in 1964. Perhaps only the Abbe de Nantes was earlier. I found this on his website:
http://www.latinmass-ctm.org/about/ourleader/1965.htm"The Catholic Traditionalist Movement has issued a manifesto deploring recent reforms in the Church's liturgy and expressing alarm at what it describes as efforts to 'Protestiantize' Roman Catholic churchgoers...The leading influence in the traditionalist group is a Belgium-born priest, the Rev. Gommar A. De Pauw, professor of moral theology and canon law at Mount St. Mary's Seminary, Emmitsburg, Md." - THE NEW YORK TIMES, March 28, 1965
"Although he was born in Belgium (1918), arriving in New York in 1949 and becoming a U.S. citizen in 1955, the ancestors of Father De Pauw-a figure of major controversy in the Roman Catholic Church-include a line of early American settlers. Among them were Michael De Pauw, the first proprietor of what is now Staten Island, New York, and Charles De Pauw, an aide-de-camp to Lafayette during the American Revolution. DePauw University in Indiana was named after one of his grand-uncles.
Father De Pauw's rise to fame from relative obscurity as a professor of moral theology and canon law in Maryland grew out of a Manifesto stating the case for the Catholic Traditionalist Movement against recent church reforms." -NEW YORK TIMES, April 3, 1965
"Father De Pauw,... a forthright priest,... at a Manhattan press conference, argued that the nation's bishops had been bamboozled into accepting reform by a few liberal theologians,... and openly challenged church policy..." -- TIME, April 9, 1965
"From the pews and even from the pulpits, intransigent traditionalists within the Catholic Church are fighting the reforms of the Vatican Council...In the U.S., the fundamentalist backlash has been led by a group calling itself the 'Catholic Traditionalist Movement'... The Rev. Gommar A. De Pauw, a 46-year-old theology professor from Mount St. Mary's Seminary in Maryland and the movement's only spokesman,... charged that the bishops in Rome had been 'seduced,' and Catholics had been 'brainwashed' by 'leftist extremists' among the council's theologians who want to 'Protestantize' the church." -NEWSWEEK, April 19, 1965
"Father De Pauw is articulate and affable, joking that he has become the 'complaint department' of the Catholic Church, but he litters his speech with intemperate words: The Catholic reforms were subtly extorted from the bishops at the VaticaCouncilil by 'no-good extremist advisers'; the revised Catholic worship is 'a test-tube pseudo-intellectual liturgy.'" -- NATIONAL OBSERVER, May 10, 1965