When some 25,000 members of the International Longshoremen’s Association went on strike last October, bringing three dozen container ports on the east and Gulf coasts of the US to a halt, there was widespread alarm. Some predictions were that, because these ports handle one-quarter of the country’s international trade, the stoppage could cost the American economy up to $4.5bn a day, reignite inflation and initiate ripple effects that would be felt across the world.

In the event, the panic lasted just 72 hours. Following hurried negotiations and the offer of a salary increase worth nearly 62 per cent over six years, the longshoremen agreed to return to work, albeit temporarily — perhaps “the most lucrative three days in labour-management history”, in the words of Patrick L Anderson, CEO of business consultancy Anderson Economic Group.

But in some ways the battle is only just getting started. Although it was the pay rise that caught the attention of the media, the union’s real issue is with automation — specifically proposals by the United States Maritime Alliance (USMX), which represents port operators and container carriers, to equip more US ports with semi-automated cranes.