A grand old family tree like the Dalrymples must be allowed to have a little deadwood in it, and anyway, do we remember Hew Dalrymple for his poetry, for his tireless efforts to bring the rule of law to Grenada, or for marrying his beautiful daughter Grace Elliot to a baronet twenty years her senior, who put her into the society that kept her as a courtesan?

When Sir Walter Scott was telling his history of Janet Dalrymple, (the model for his Bride of Lammermoor and Gaetano Donizetti's Lucia de Lammermoor, he claimed of the many titles and honours of the Dalrymple's that "The talents of this accomplished race were sufficient to have accounted for the dignities which many members of the family attained, without any supernatural assistance."
Which is as close as you get to unmixed praise from a posthumous biographer that is not related to you.

I know two other Persuasion-relevant Dalrymples that history is not so kind to: As an Australian, I feel very obliged to the British Naval Hydrograher Alexander Dalrymple, even if his theory of Terra Australis Incognita was utter bunkum, and the great expeditionary voyages of Byron (grandfather of the poet), Carteret, and Wallis were all in vain.

Of course, these great hearts of oak had all departed by 1814, but there was another Dalrymple, Lieutenant-General Hew Whitefoord Dalrymple, an army man who had been govener of Gibralter, and had relieved Wellesley of his command and negotiated the infamous convention of Cintra in 1808. This Dalrymple was known by his brothers in arms as "the Dowager" for his old-womanish ways.
Francis Austen had a part to play in this buisness - he was then the captain of HMS St. Albans and charged with conveying a packet of transports, full of British soldiers and French prisoners, to the Spithead. It seems that he felt strongly enough for the future Duke of Wellington's situation , to deviate from his orders slightly to help him out, as he reveals letter to W. Wellesly Pole (older brother of Wellington)that I have taken from Jane Austen's Sailor Brothers:-
St. Albans OFF THE BUHLINGS, August 18, 1808.

SIR,—I have to state to you for the information of my Lords Commissioners of the Admiralty, that in consequence of intelligence respecting the British Army in Portugal, communicated by Captain Hotham, of his Majesty's ship Defiance, on the 12th inst. off Corunna, Brigadier-General Anstruther commanding the troops embarked on board the transports under my convoy, requested us not to pass Figuera without affording him an opportunity of obtaining some further intelligence relative to the situation of Lieutenant-General Sir Arthur Wellesley; with this, from existing circumstances, I thought it my duty to comply, although contrary to the strict letter of my orders, and accordingly when round Cape Finisterre, steered for Cape Mondego, off which I arrived at noon on the 16th. The Brigadier-General receiving there orders to proceed along the coast to the southward and join the convoy under his Majesty's ship Alfred, whose captain would give him further information respecting the position and operations of the army by which he was to guide his own, I proceeded in consequence thereof with the fleet, and yesterday at 1 P.M. joined the Alfred off Phenice.

At four o'clock, in compliance with the Brigadier-General's wish, I anchored with the transports under the Burlings, to prevent their dispersion, and to await the arrival of directions from the Lieutenant-General, to whom an aide-de-camp was yesterday despatched to announce our arrival, force, and position.

One of my convoy, having a detachment of the 2nd battalion of the 52nd Regiment on board, parted company on the night of the 12th instant, and has, I suppose, in compliance with the secret rendezvous I issued on the 23rd of July, proceeded off the Tagus.

I have the honour to be, Sir,
Your obedient humble servant,
FRANCIS WILLIAM AUSTEN."

Carteret had a never-married son who had become a captain in the navy during the war. He served in the evacuation of the disastrous Walcheren campagin, and had been reported (in a pamphlet circulating in Portugal whose author designated himself one of Carterets 'ships company')as running from a disabled French frigate in 1813, but had been aquitted at the court martial he insisted on holding to clear his good name, and was made a Companion of the Order of Bath (an honour that had been expanded by the Prince Regent in 1815 "to the end that those Officers who have had the opportunities of signalising themselves by eminent services during the late war may share in the honours of the said Order, and that their names may be delivered down to remote posterity, accompanied by the marks of distinction which they have so nobly earned." These did not take precedence over a baronet, but Carteret actually ended up inheriting a baronetcy as well.