Relations between Siward and King Edward appear to have been good. Neither Siward nor any associates of Siward were punished by Edward in later years. In fact, Siward appears to have been one of Edward's most powerful supporters. On 16 November 1043, Siward, along with Earls Godwine of Wessex and
Leofric of Mercia, marched with King Edward against his mother,
Queen Emma, helping the king to deprive the queen of her huge treasury. Edward then accused Emma of treason and deposed
Stigand,
Bishop of Elmham, from his position "because he was closest to his mother's counsel". The Norman propagandist and historian,
William of Poitiers, claimed that Siward was among those who had sworn an oath to uphold Edward the Confessor's alleged declaration that
William II, Duke of Normandy (later King William I), was to be his heir. Others said to have made that oath were Earls Godwine of Wessex and Leofric of Mercia, along with Stigand, who had been pardoned in 1044, and raised to
Bishop of Winchester in 1047. If this did happen, it was probably during or a little before spring 1051, when
Robert,
Archbishop of Canterbury, was journeying to Rome for his
pallium. In 1051 Siward, along with Earls Leofric and
Ralph the Timid, mobilised forces in defence of the king against a rebellion by Earl Godwine and
his sons. The
Anglo-Saxon Chronicle relates that although Siward had to call up reinforcements, King Edward was successful and Earl Godwine was temporarily exiled. Earl Godwine remained a threat in exile, and the continued "belligerent support" of Siward and Leofric was thus vital to King Edward's safety. It was apparently, however, the reluctance of these two earls to fight Earl Godwine that contributed to Godwine's re-establishment in England in 1052. There is evidence to suggest that Siward extended his power southward, bringing the
shire of Northampton into his control in the 1040s and the
shire of Huntingdon in the 1050s. The evidence comes from royal
writs addressed to Siward as earl in these shires. Siward's predecessors as earl in these areas were other Scandinavians, Thuri and
Bjorn son of
Earl Ulf; the former was styled "earl of the Midlanders" (
comes mediterraneorum), showing that this earldom represented the earlier polity of the
Middle Angles of Mercia. It was this area, rather than Northumbria, to which Siward's descendants were most attached. Likewise, it has been argued that Siward brought
Cumberland, thought by some historians to have been lost to Strathclyde, back under Northumbrian lordship. The evidence comes from a document known to historians as "Gospatric's Writ". This is a written instruction, issued either by the future
Gospatric, Earl of Northumbria, or Gospatric, son of Earl Uhtred, that was addressed to all Gospatric's kindred and to the notables dwelling in the "all the lands that were Cumbrian" (
on eallun þam landann þeo Cōmbres); it ordered that one Thorfinn mac Thore be free in all things (
þ Thorfynn mac Thore beo swa freo in eallan ðynges) in
Allerdale, and that no man is to break the peace which was given by Gospatric and Earl Siward. Historians such as Charles Phythian-Adams believed that such phraseology indicated that Siward conquered the region from its previous rulers, although others, like William Kapelle, believed that the region had come, were it ever lost, back into English power before Siward's time. A little can be said about Siward's relations with the Northumbrian church, in particular with regard to his relations with
Durham. As a result of Siward's marriage to Ælfflæd, Siward gained possession of a group of estates in
Teesside claimed by the bishops of Durham. Acquisition of these estates might have brought opposition from the
Bishop of Durham, but
Æthelric the incumbent had been expelled by the clergy of Durham in either 1045 or 1046 and, according to the
Libellus de Exordio, only returned by bribing Siward. According to the
Libellus, the clergy were "terrified and overwhelmed by the fearful power of the earl" and "were compelled willy nilly to be reconciled to the bishop, and to admit him into his episcopal see". Despite this, Siward escaped censure in the writings of later Durham monks, something which suggests relations between Siward and Durham were probably good in general. Siward can be found witnessing numerous charters during Edward's reign, though not as many as the Godwinsons; Siward usually comes third in lists of earls, behind Godwine and Leofric but ahead of Godwine's sons and the other earls. He witnessed at least seven, possibly nine, extant charters in 1044, six or seven in 1045, two in 1046, one in 1048 and one in 1049. A
Dux ("earl") named Sihroþ and Sihroð witnessed two charters in 1050, and this may be Siward. There is another attestation in 1050, and his name appears in two dubious witness lists attached to charters dating to 1052 and 1054. Possibly Siward's last historical appearance in English legal documents is in the agreement made—probably at
Lincoln—between
Wulfwig,
Bishop of Dorchester, and Earl Leofric, dating to between 1053 and 1055. ==Expedition against the Scots==