The start of actual tunneling was delayed due to dispute between a dockworkers' union, which was commissioned to dig the tunnel, and a sandhogs' union, which claimed that its members were entitled to work on the project because the sandhogs specialized in building tunnels. This disagreement turned into a violent protest and multi-day strike in February 1941. The next year, some union sandhog workers were banned from working on the Battery Tunnel project due to a disagreement with their union's parent union.