La Verendrye in his fort on Lake Winnipeg was in a desperate position.  He made a hasty journey back to Montreal and even Quebec, to beat up funds and to pacify the capitalists of his fur-trading monopoly.  He painted in glowing colours the prospects of cutting off the trade of the Hudson’s Bay Company and the building up of an immense commerce in valuable furs, and these men agreed once again to furnish the funds for the extension of the expedition.  On his return he took back with him his youngest son, Louis, a boy of eighteen.  Whilst he had been absent from Fort St. Charles (a post which he had built on the Lake of the Woods, in communication by water with the Winnipeg River), on Lake Winnipeg, that place was visited by a party of Siou Indians.  They found the fort occupied in the absence of the French by a number of Kri or “Knistino” Indians in French service.  These Kris were frightened at the arrival of the Sious and fired guns at them.  “Who fired on us?” demanded these haughty Indians from Dakota, and the Kris replied, “The French”.  Then the Sious withdrew, but vowed to be completely revenged on the treacherous white man.

When La Verendrye reached Fort St. Charles its little garrison was almost at the point of starvation.  He had travelled himself ahead of his party, and the immense stock of supplies and provisions he was bringing up country were a long way behind him when he reached the fort.  He therefore sent back his son Jean, together with the most active of his Canadian voyageurs and the Jesuit missionary, in order that they might meet the heavily laden canoes and hurry them up country as fast as possible.  But this party was met by the Sious on Rainy River, who massacred them to a man.  They were afterwards found lying in a circle on the beach, decapitated and mutilated.  The heads of most of them were wrapped ironically in beaver skins, and La Verendrye’s son, Jean, was horribly cut and slashed, and his mutilated, naked body decorated with garters and bracelets of porcupine quills.

Meantime, during his absence in Lower Canada, two of his sons in charge of Fort Maurepas, on Lake Winnipeg, had been very active.  They had discovered the great size of this lake, and also the entrance of the Red River on the south.  They then proceeded to explore both the Red River and its western tributary the Assiniboin.  On the Assiniboin was afterwards built the post of Fort La Reine, and from this place in 1738 La Verendrye started with two of his sons, several other Frenchmen, a few Canadian voyageurs, and twenty-five Assiniboin Indians.  Leaving the Assiniboin River, they crossed the North Dakota prairies on foot.  Owing to the timidity of his Indian guides, La Verendrye was not led direct to the Missouri River, the “Great River of the West”, but along a zigzag route which permitted his guides to reinforce their numbers at Assiniboin villages, and every now and then join in a bison hunt.  All the party were on foot, horses not then having reached the Assiniboin tribe.  But on the 28th of November, 1738, they drew near to the Missouri and were met by a chief of the great Mandan tribe, who was accompanied by thirty of his warriors, and who presented La Verendrye with young maize cobs and leaves of native tobacco, these being regarded as emblems of peace and friendship.