I was first introduced to this combo in a 3-player real-space Dominion game. My two opponents went for Royal Carriages and Bridges with an eye towards Duchies and Dukes. I decided to employ a more boring big-money approach and grab Provinces, hoping that they would split Duchies. I was impressed with the synergy between Royal Carriage and Bridge as my opponents were grabbing Duchies and Dukes, but the game was pretty even when Duchies and Dukes ran out; I thought I might have a chance to grab the remaining Provinces and win. My eyes were opened when one of my opponents had a post-green mega-turn and bought 4 Provinces. That got me thinking: this isn't just synergy, this is a combo.
Bridge is the key. The more you play, the more value each Bridge provides. 7 is the magic number where you can trivially buy 8 Provinces. It is very hard to play 7 Bridges in one turn. In fact, I think there are only three realistic ways:
- Native Village
- King's Court (with a supporting engine)
- Royal Carriage
The first two have combo articles on the wiki. Royal Carriage does not. I will go further. I think Royal Carriage might be the best combo piece for Bridge. The Native Village strategy relies on obtaining 7+ Bridges and 6+ Native Villages. If either of these piles are in contention, it fails pretty hard. Also, in my limited experience, it is slow unless you can buy out both piles (and then you have to fear a 3-pile ending). King's Court and Bridge is fast and powerful and only requires a few components, but it is conditional on a lot of support. Non-terminal draw is key, and trashing or sifting are also needed. Royal Carriage and Bridge does not rely on as many components as Native Village and Bridge and does not require support (but it is aided by it).
I played a few Solitaire games with nothing else in the kingdom. In all games, I limited myself to 7 Royal Carriages (important) and 5 Bridges (less important) - to simulate some contention over these cards. Because the strategy involves rushing to Royal Carriages, I think it is fair to suppose that one wins the split, but it's worth testing how good the strategy is with 5 or 6 Royal Carriages. My best game resulted in 8 Provinces on turn 12. I recorded what I bought on each turn, but not what I had in hand or played.
Turn 1: Buy Bridge
Turn 2: Buy Silver
Turn 3: Buy Royal Carriage
Turn 4: Buy Silver
Turn 5: Buy Royal Carriage
Turn 6: Buy Royal Carriage
Turn 7: Buy nothing (I must have had 3 Estates)
Turn 8: Buy Royal Carriage
Turn 9: Call 2 Royal Carriages and buy 3 Royal Carriages and a Bridge
Turn 10: Buy Bridge
Turn 11: Buy nothing (my hand included a lot of Royal Carriages)
Turn 12: Call 6 Royal Carriages and buy 8 Provinces.
I followed that up with another game with very poor shuffle luck (Bridge and Silver both missed turns 3 and 4 and my luck didn't much improve). I still managed to get 7 Provinces and 3 Duchies by turn 16.
Turn 1: Buy Bridge
Turn 2: Buy Silver
Turn 3: Buy Silver
Turn 4: Buy Silver (*groan)
Turn 5: Buy Royal Carriage and Silver
Turn 6: Buy Bridge
Turn 7: Buy nothing (I must have had 3 Estates)
Turn 8: Call a Royal Carriage and buy two Royal Carriages and a Silver
Turn 9: Buy Royal Carriage and a Bridge
Turn 10: Buy Royal Carriage and a Bridge
Turn 11: Buy Silver (I chose not to call a Royal Carriage)
Turn 12: Buy nothing (I might have had enough for a Silver, but I didn't want it at this point)
Turn 13: Buy Royal Carriage (right before my last shuffle)
Turn 14: Duchy
Turn 15: Duchy
Turn 16: Call 6 Royal Carriages and buy 7 Provinces and a Duchy (I must not have had any treasure in my hand).