Complex sentence: In March 1916, the battalion sailed to France and deployed to the Somme, seeing action at Pozières in July 1916, followed by Ypres, in Belgium, before returning to the Somme in winter.
Split into simpler sentences: In March 1916, it sailed to France and deployed to the Somme. Later the battalion fought at Ypres, in Belgium, before returning to the Somme in winter.