 Complete the following phrase:  In September 1915, Cuza stepped up his opposition to PND policies, joining Nicolae Filipescus Unionist Federation. According to Iorga, the latter group perverted the nationalist cause, using its symbols in an attempt to topple and replace Brătianu. The highly inactive PND eventually suspended its activities in September 1916, some time after Brătianu had declared war on the Central Powers. The party was thus non-existent during the 