Complex sentence: On 22 March, the KAR companies attacked but withdrew to the south when a planned Belgian assault failed to materialise; the Italians were surprised by the flanking manoeuvre and retreated to Saïo.
Split into simpler sentences: On 22 March, the KAR companies attacked but withdrew to the south when a planned Belgian assault failed to materialise. Nevertheless, the Italians were surprised by the flanking manoeuvre and evacuated to Saïo.