Complex sentence: At three divisional artilleries began a standing barrage on the trench and a creeping barrage on no man's land, in thick fog, movement was so difficult that the barrage moved at in ten minutes.
Split into simpler sentences: At three divisional artilleries began a standing barrage on the trench and a creeping barrage on no man's land, in thick fog. Movement was so difficult that the barrage moved at in ten minutes.