Complex sentence: To either flank was thick jungle and swamp; dispersed through the area were relatively open patches of kunai grass, one immediately forward of the Japanese positions encountered by the 2/1st Battalion on 20 November.
Split into simpler sentences: To either flank was thick jungle and swamp; dispersed through the area were relatively open patches of kunai grass. One patch was immediately forward of the Japanese positions encountered by the 2/1st Battalion on 20 November.