Engineers.Thus the officers of the Fiftieth New York Engineers celebrated the victories of Gettysburg and Vicksburg in front of Petersburg July 4, 1864. At the head of the table sits Lieutenant-Colonel Ira Spaulding. On his right is Charles Francis Adams, later a leading American historian. Often in front of Petersburg just a few more shovelfulls of earth meant the saving of lives. The veterans in the lower photograph are bearded and bronzed; the muscles beneath their shabby blue tunics were developed by heavy, constant manual labor. The operations in this campaign marked a development in field-fortifications, opened virtually a new era in warfare. The siege was not a bombardment of impregnable fortifications. It was a constant series of assaults and picket-firing on lines of entrenchments in the open. By July, 1864, the earthworks to the east had been almost finished, although much of this exacting labor had been performed at night and under a galling fire. During August, the engineer corps extended the lines south and southeast of the beleaguered city. But meanwhile the Confederates had been hard at work also. They had fewer men to hold their lines and to carry on the work, but it was accomplished with great devotion, and under able management and direction. The soldiers in the trenches lived in bomb-proofs.