Complex sentence: An intermittent bombardment began on 11 July but it was not as heavy as on 1 July and so did not signal so obviously the British intentions to attack and emphasis was placed on counter-battery fire, to eliminate the German guns.
Split into simpler sentences: An intermittent bombardment began on 11 July but it was lighter that on 1 July and so did not signal so obviously British intentions. Emphasis was placed on counter-battery fire, to eliminate the German guns.