From page 37 of this thread:
D. von Staberg wrote:the army of Gustav Adolf the Great (aka Gustav II Adolf, Gustavus Adolphus) which fought in war with Poland 1621-1629.
Swedes won battles of Wallhof/Walmojza, Mewe/Gniew, Mohrungen, Dirschau/Tczew and Gorzno.
Poles won battles of Hammerstein/Czarne and Honigfelde/Trzciana.
Neither side had an outright victory so in 1629 both sides agreed to a truce which favoured the Swedes. Swedish army which had learnt its leasons in the hard school of the Polish war then went on to fight in the 30-years war were it defeated the 'invicible' Catholic army commanded y Tilly. It was only after defeating the best armies in both western and eastern europe that the Swedish soldiers were considered the best in the world. And fighting woth the Poles was only a small victory, as swedish cavalry soldier said. "I would rather fight alone against 3 Germans than gainst one Pole."
The battle of Walmozja (Wallhof) of 1626 was part of another war - war in Livonia. And it was a Swedish ambush / surprise attack against completely unprepared and smaller forces, rather than a regular field battle.
We do not count it as part of the Prussian War of 1626-1629, anyway.
The only battle of Mohrungen (Morąg) about which I have heard was fought in 1807 - so I guess you confused something (or maybe it is some unknown and rather small battle, about which I haven't heard?).
The battle of Gniew (Mewe) ended in such a way, that neither side managed to destroy the enemy, while maneuver of the Polish army after the battle prevented the Swedish army from capturing Danzig (Gdańsk), which was the main Swedish goal in this war. So this battle should be described as tactically inconclusive and strategic Polish victory. Had the Swedish army defeated the Polish army at Gniew, Danzig would have fallen to the victorious Gustavus Adoplhus (since it had not been prepared for defence yet, at that time when the battle of Gniew was fought). But the Polish army - although it also failed to destroy their enemy (just like Swedish army failed to destroy the Polish army) - managed to stop the Swedish advance on Danzig. So strategically this battle was a Polish success.
The battle of Tczew was also tactically inconslusive. The first day of this battle was relatively unfavourable for the Polish side. It ended in defeat of a Polish cavalry detachment inflicted by a charge of numerically superior Swedish cavalry (superiority was like 2:1 in favour of Swedish Reiters - see below) - some historians describe this clash as the first victory of Swedish cavalry over Polish-Lithuanian cavalry in history (in fact there was at least one such case before - also see below). Polish army lost 80 killed and an unknown number of wounded on the first day of the battle. These are relatively heavy losses compared to achievements - especially when we compare this to battles like Kircholm, in which Polish-Lithuanian forces often inflicted crushing defeats on the enemy while suffering not much higher losses. But in relation to the size of the entire Polish-Lithuanian army at Tczew, 80 killed is a drop in the sea. But the 2nd day of the battle was more favourable for the Poles. Gustavus Adolphus was wounded and the Swedish army retreated - the battlefield remained in Polish hands. Hardly a Swedish victory.
Historian R. Sikora concludes about importance of various field battles of this war in Prussia (1626-1629):"(...) only 3 battles of this war - Gniew, Czarne and Tczew - could radically change its outcome, and only in case if Swedish forces defeated Polish forces in these battles, which, as we know, did not happen. The defeat of Swedish forces (which happened only in the battle of Czarne of these 3) could not decisively change the result of the entire war. But let's go even further in our considerations. Would the seizure of Danzig by Swedish forces mean the end of this war - the end favourable for Sweden? Even though after capturing Danzig they surely would have been very close to winning the war, such a scenario is not the only option. We can also imagine a totally different scenario. The seizure of Danzig by Swedish forces would have been such a heavy blow to Poland, such a heavy impulse, that it would enforce the acceptance of nobility for the reform of state's finances. Let's remind that in 1627 such a reform nearly took place. Only the lack of activity of the king on this field, as well as not so bad situation on the Polish-Swedish front, contributed to the fact, that in the end radical propositions of reforms compiled by the Warsaw Commission were not implemented and remained on paper. It is rather sure, that with strong financial grounds the Polish army would be able to fight a prolonged war and regain the losses, unless... Unless states hostile to the PLC would consider the loss of Danzig as a strong enough signal of its weakness and would ally with Sweden against the PLC. What would happen then? In such case there are so many probable options, that we will leave them without further comment. (...)"Source:
R. Sikora, "Polish military in the age of the Polish-Swedish war 1626-1629. Crisis of a superpower", pp. 244-245.
Regarding Swedish Reiters vs Polish cavalry in the battle of Dirschau:"Polish and Swedish forces camped near Dirschau (Tczew). They were separated from each other by swamps of Motlava river, with a narrow weir as the only available pass across them. Before noon on 07.07.1627 Swedish Reiters attacked forward outposts of Polish forces, located in front of the weir. The aim of this attack was to provoke Polish forces to cross the weir and fight on the Swedish side of Motlava swamps. In such case the Polish army would have swamps behind its back. Koniecpolski indeed sent reinforcements to those Polish outposts. He crossed the weir with almost entire Polish cavalry, hoping to finally fight an open field battle. Swedish forces retreated back to their camp. Koniecpolski proceeded behind them. But when he saw, that Swedish forces concealed themselves behind a cover of earthworks, he halted further advance. He sent forward skirmishers to provoke the Swedes to come out of hiding. But they didn't show even the slightest desire to do so. After two hours of waiting in vain, Koniecpolski started to withdraw his cavalry back to the Polish camp. When almost entire cavalry already crossed the weir back to the Polish side of Motlava swamps, Swedish Reiters suddenly attacked the last units of the Hetman's Regiment remaining on the Swedish side of swamps, that is 4 banners of Hussars and 2 banners of Pancerni. The attacking Swedish cavalry had considerable numerical superiority [the attacking Swedish force had 3 squadrons - each squadron typically had 4 companies, each company had a "paper strength" of 125 horsemen - Domen]. The surprise effect was double. Poles did not expect an attack - but especially an attack carried out in such a style - Swedish cavalry charged with cold steel. Polish units were dispersed. Swedish attack was repulsed not until it encountered Polish infantry entrenched behind earthwork defending access to the weir. Losses of the Polish army during the entire first day of the battle (07.07.1627) amounted to 80 killed and an unknown number of wounded."Source:
R. Sikora, "Polish military in the age of the Polish-Swedish war 1626-1629. Crisis of a superpower", page 162.
Let's just add that 4 banners of Hussars and 2 banners of Pancerni could number ca. 630 horsemen (we know from sources that the entire Hetman's Regiment numbered ca. 1500 horsemen - 800 Hussars and 700 Pancerni - while it had in total 7 banners of Hussars and 8 banners of Pancerni, so it seems that a banner of Hussars in this Regiment numbered on average 114 horsemen, while a banner of Pancerni - 88 horsemen).
So the Swedish cavalry could have up to 2:1 numerical superiority in this clash (even ca. 1200 Reiters - "paper strength" would be 1500, but it is impossible that Swedish squadrons & companies were all at full strength by the start of the battle of Dirschau, even 100 per company is quite optimistic).
Anyway - each Polish-Lithuanian Hussar / Pancerni banner numbered about as many horsemen as each Swedish Reiter company.
And Swedish cavalry in this confrontation had 12 companies (3 x 4), while Polish cavalry - 6 banners (4 + 2).
"Officially" (and many historians repeat this false information) this clash on 07.07.1627 was the first defeat of Polish-Lithuanian cavalry in combat against Swedish cavalry in history. In fact there was at least one earlier example of Swedish cavalry taking the upper hand. In the battle of Koknese on 23 June 1601 - which, as a whole, was victorious for the PLC - Swedish cavalry charge defeated the Polish-Lithuanian left wing, which consisted of 200 infantry with 5 guns supported by 200 - 300 cavalry (but exact composition of this cavalry is unknown - we don't know if those were Hussars, some other type of cavalry, or maybe mixed units of a few types). Cavalry of the Swedish right wing which did it at Koknese, had huge numerical superiority. The Polish-Lithuanian left wing was defeated - only counterattack of 3 banners of Winged Hussars repulsed the Swedish charge and defeated the temporarily victorious Swedish cavalry. In the meantime 1600 cavalry of the Polish-Lithuanian right wing charged and defeated the Swedish left wing. And the entire battle was won by Polish-Lithuanian forces.