Arundel was with Henry at Westminster for Christmas 1414. As one of the king's close friends, he displayed the cardinal virtues of loyalty to the Lancastrian monarchy, as well as enjoying the honour of personal comradeship. Some lords remained loyal to Richard II and threatened rebellion throughout the North. There were those on the Welsh Marches, such as the Chamberlain of Chester who had deserted to Owain Glendower. The new King
Henry V restored the Earl of Arundel to a place of influence, immediately appointing him Lord Treasurer, as well as constable of
Dover Castle and
Warden of the Cinque Ports. On 19 March 1415, The Lord Warden was ordered to summon and array seamen for forthcoming fleet operations: 57 ships from the Cinque Ports in 40 days were expected to assemble. No ship of more than 20 tuns was permitted to leave port. All requisitioned vessels were to be taken to Southampton by 8 May. On St George's Day at Windsor Arundel was made a Knight of the Garter with precedence. He was among 16 of the 25 knights preparing for war that summer. The following day 24 April, the king rewarded his friend with an additional £300 on top of a modest salary as Lord Treasurer of £100 per annum. Arundel's experience deploying massed ranks of longbowmen was vital to Henry's strategy to succeed; as many as 2,000 had been used at St Cloud. But the invasion date was put back to 1 July, at the end of April. On 15 June a service was held at St Paul's; Arundel could not have known he would not return in triumph, so he lingered at least until 24 June. Meanwhile, he was despatched on an expedition "into parts of Wales" to raise more archers to add complement to existing units. The royal household paid him £18 12s expenses, but the coffers being bare, Arundel's troops did not receive all their wages. On 27 May 1415, Arundel and Thomas Beaufort had been put in charge of provisioning Calais and the army in Normandy. This included a scheme devised by the Keeper of the Privy Seal to extort money out of Italian merchants in London that raised nearly £2000. As they were about to leave (8 August) Southampton by ship, King Henry replaced Arundel with a new Treasurer,
Sir John Rothenhale; Arundel was on the campaign to fight. He wrote a will signing over his estates to trustees for his wife, Beatrice, Countess Arundel and the children for which he gained the King's consent.
Noblesse oblige was one of Arundel's personal chivalric codes. When it was revealed the earl of March was inveigled into the Southampton Plot, Arundel and Lord Scrope provided the bulk of the 10,000-mark fine imposed by Henry for this
illegal marriage to Anne Stafford. Arundel's astute business dealings saved March and the King at the Michaelmas Council, which was in uproar. Bishop Richard Countenay of Norwich had died, the Duke of Clarence was ill, but Arundel remained the King's "great friend". The Southampton plotters attempted to implicate Arundel, but as their testimony unravelled it became clear Sir Thomas Gray was speaking spiteful lies, and the young earl was held to be without blame. Arundel was one of the initial commanders of Henry V's 1415 French campaign, he sailed with a minimum one hundred men-at-arms, and three hundred archers. Of his own retinue two men-at-arms and thirteen archers died at the
siege of Harfleur. At least 14 men-at-arms and 68 archers were sick, and sent home on the Feast of St Wenceslas (29 September); Arundel was among them with five men-at-arms to help him. The Council advised the king against a proposed march to Calais, but Arundel had to return to Sussex on 10 October 1415. He was nursed by a faithful retainer's wife, Elizabeth Ryman. In his will made on 10 October, he asked to be buried in the church of the Holy Trinity, Arundel. He left 200 marks for a funeral, and required a statue be erected over his father's grave. He had pledged a vow to pray to St John of Bridlington when he was a servant of Prince Hal; and now at Mary Gate, Arundel, a chapel was to be built dedicated to the Virgin. Arundel wanted all the wages arrears to be paid by his heirs that were owed to the soldiery. ==Ancestry==