Slitherine

My question relates to gameplay and creating pontoon bridges. Could you help describe how this is done? When I deploy and engineering unit (US orBritish), adjacent to a river hex, do don’t know how to create a pontoon bridge. Does the
unit need to be in a certain hex for a number of turns? Thank you! (BTW - i'm thoroughly enjoying the game...thanks )

You'll have to move the engineer onto the river tile.
On the next turn there'll be a bright white tile on the abilities panel (bottom left side of the UI) looking like a bridge with two arches (if you have enough resource points to pay for it).
The tooltip will say something like build/deploy pontoon bridge.

Thank you! Much appreciated