 Complete the following phrase:  In the air the strength of the enemy continued the same as it had been since the previous spring. A few pursuit patrols of Fokker airplanes were reported as operating in this sector, but it was quite probable that these were new airplanes received as replacements for the Albatross and Pfalz type formerly in use. Individual observation and photograph airplanes operated over the sector, but no unusual number of hostile aircraft was at any time encountered or reported before the opening of the 