I'm afraid this subject needs its own thread, even though its a spinoff of thinking about aspects of snippet #20.
Given I've been shouting for years about how critical taking the Salthar-Silk Town Canal is and various ways it could be done by small company sized teams of scout snipers etc, it's rather embarrassing that it suddenly occurred to me only a few days ago that the new smaller River II class ironclads [I realise they're really steel armored, but they're still being called ironclads] are probably small enough for not only the Salthar locks, but those of the Dairnyth-Alyksberg Canal at the north end of the Seridahn River, so they could get to the Bay of Bess far sooner than I'd previously considered.
That is, once the next obstacle in the Seridahn has been cleared and the river secured up to the Dairnyth-Alyksberg locks, they could enter and steam all the way to the Bay quite quickly [~2 days], before the RDA or Go4 could react effectively, especially assuming no further locks on the canal west of the Seridahn River, NTM I have very high confidence in the ICA engineers to repair or replace the locks fairly quickly if they are damaged or destroyed.
Part of my reasoning is that I don't think the Dohlarans know about these smaller ironclads in the first place, nor their potential for using smaller locks.
I suspect the reports of the "Great Canal Raid" included first hand descriptions of the Delthak 'River' class size relative to the locks, which were much bigger than most on the continents, if not the biggest.
While I'm confident the Go4 orders to prepare all the remaining locks for demolition have been followed, I believe there is some smug complacency or too much overconfidence, that because 'their locks' are too small for such vessels, they really don't have to worry about doing something so seemingly heretical, so opposed to the far more comfortable centuries of the Writ's condemnation of damaging the canals in the first place.
Thus, being very understandably focused on his own predicament [in the process of retreating back to Dohlar], Rychtyr will leave the upper Seridahn and Dairnyth canal to those who have that duty, assuming they're prepared to do it well, and be among the first to be shocked by the news of up to a squadron of ironclads passing Dairnyth on the now wider Fairmyn River, pausing only to smash the city's obsolete defenses [bombard cannon etc] before entering the Bay of Bess.
Another squadron or possibly only half would have already entered the Fairmyn river and in about 4 days steam up to the Charayn Canal locks, which are blown before them [as the alliance expected] to capture or destroy around 5 5days worth of Kaitswyrth's supplies on the river, nearly 3 times EHM's daily needs; not an insubstantial contribution to his advance to Dairnyth and the defense of the city and river against any MHoGatA sub-army sent south from the Langhorne-Bedard Canals.
While Sharpfield's fleet may not yet risk patrolling the Bay of Bess yet, sending a nimble squadron of schooners to help scout and patrol the Bay's narrows, would mean a squadron of River II class ironclads could effectively blockade the last 600 miles to Dairnyth, preventing supply from much further away.
The question then becomes how much and for how long could the local TL farmers and fishermen support a 400K army in a siege.
While it was traveling along the shoreline high road, it might consume a 5days' worth of food and fodder from the 1600 square miles it passed that day [that area within 1 day's travel of the 40 miles marched] as directed by the CoGA; quite bearable to the locals, especially if they have two harvests a year [I doubt it, being around 2600 mile north of the equator]; figuring a Border state average population of ~17 per mile, though those on the coast could well be 2-3 times that density due to the much better weather and economic opportunity etc.
This may be an opportunity for RFC to detail the more traditional Safehold siege, and the logistic advantages dragons provide in reducing the supply concerns we're familiar with from Earth's history.
Because, thanks to dragons, local fodder won't run out in a week as it did in Earth's sieges before steam power.
EHM would be defending behind a river at least several miles across according to the maps, far too wide for the MHoG's artillery; while his (including mortars) would have plenty of time against every boat's inexperienced rowers, not too mention the ironclad patrols that would probably destroy any concentration of barges, fishing boats, etc that the MHoG tried to collect for such attempts.
The combination of a mobile defense and ironclads could bottle up a quarter, even half of the MHoG, which could provide plenty of time for other developments in Dohlar and elsewhere that would also benefit the allies.
Does my supposition make sense?
Could RFC have distracted us by the obvious Salthar-Silk Town canal?
I await your wise comments.

L