In International Ass'n of Machinists v. N.L.R.B., 1940, 311 U.S. 72, 61 S.Ct. 83, 85 L. Ed. 50, there had been a long history of management favoritism to the established and hostility to the aspiring union; and in Franks Bros. Co. v. N.L.R.B., 1944, 321 U.S. 702, 703, 64 S.Ct. 817, 818, 88 L.Ed. 1020, the employer had "conducted an aggressive campaign against the Union, even to the extent of threatening to close its factory if the union won the election."