The manager may try to persuade you to stay, but there is no such thing as “doesn’t allow you to resign”. There is no slavery in Singapore; you are always allowed to resign.

The manager will then have to work closely with the resourcing team to find replacements for the entire team. Depending on availability, it may not for a 1 for 1, grade for grade replacement. The replacement team, with no prior experience, will naturally have a harder time continuing where your team left off. The manager has to facilitate this handover and guide them accordingly, becoming more hands on for this engagement.

Depending how flexible the timeline is, the manager may have to manage the clients expectations to see if the signing dates can be pushed back - likely not possible if it’s a group requirement. In which case, you can expect the next team to be putting in extra hours as they learn and work simultaneously.