Complex sentence: Some of the largest ships the United States had to send through the canal were aircraft carriers, particularly "Essex" class; they were so large that although the locks could accommodate them, the lampposts along the canal had to be removed.
Split into simpler sentences: Some of the largest ships the United States had to send through the canal were aircraft carriers, in particular the "Essex" class. These were so large that, although the locks could hold them, the lamp-posts alongside the canal had to be removed.